added dnsdigger, dnswalk and some scripts
This commit is contained in:
parent
3448a3ef60
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19 changed files with 3095 additions and 0 deletions
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@ -17,3 +17,6 @@ nslint is a lint-like program that checks DNS files for errors. DNS or Domain Na
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# dnswalk
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# dnswalk
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dnswalk is a DNS debugger. It performs zone transfers of specified domains, and checks the database in numerous ways for internal consistency, as well as accuracy.
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dnswalk is a DNS debugger. It performs zone transfers of specified domains, and checks the database in numerous ways for internal consistency, as well as accuracy.
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# dnsdigger
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DNSDigger is a programm to gather as much as possible informations from DNS Servers.
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1
dns/dnsdigger/dns-server.dat
Normal file
1
dns/dnsdigger/dns-server.dat
Normal file
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@ -0,0 +1 @@
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217.5.115.7
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325
dns/dnsdigger/dnsdigger.pl
Normal file
325
dns/dnsdigger/dnsdigger.pl
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@ -0,0 +1,325 @@
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#!/usr/local/bin/perl
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# (c) 2003 Michael Thumann
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# Distribute freely
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# DNS Module from Michael Fuhr, Thankx Michael ;-).
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use Net::DNS;
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sub get_axfr{
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print "\nInitiating Zone Transfer ...\n";
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$res->usevc(1);
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@zone = $res->axfr($domain);
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if (@zone) {
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foreach $rr (@zone) {
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$rr->print;
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}
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print "\n----------------------------------------------------------------------\n\n";
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return 1;
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}
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else {
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print ';;Zone transfer failed: ', $res->errorstring, "\n";
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print "\n----------------------------------------------------------------------\n\n";
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return 0;
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}
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}
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sub find_rootserver{
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$res->usevc(0);
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if (open(ROOT,"root-servers.dat")){
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while (<ROOT>){
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chomp($_);
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$res->nameservers($_);
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print "Asking Root Server $_\n";
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$packet=$res->send($domain, 'NS');
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if ($packet){
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@additional_tld = $packet->additional;
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if (@additional_tld) {
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foreach $rr (@additional_tld) {
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$tld=$rr->rdatastr;
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if (find_ns()){close(ROOT); return 1;}
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else {print "No Records found!\n";}
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}
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}
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}
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}
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close(ROOT);
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return 0;
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die "Can't connect to the Root-Servers! \n";
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}
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else {die "Can't open root-servers.dat!\n";}
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close(ROOT);
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}
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sub resolve_name{
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# Enter the IP of your favorite DNS Server in the next line
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#$res->nameservers('217.5.115.7');
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if (open(DNS,"dns-server.dat")){
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while (<DNS>){
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chomp($_);
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$res->nameservers($_);
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}
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}
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close(DNS);
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print "Resolving $name\n";
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$packet_resolve=$res->send($name,'ANY');
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if ($packet_resolve){
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@nameserv = $packet_resolve->answer;
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if (@nameserv) {
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foreach $rr (@nameserv) {
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$ns=$rr->rdatastr;}
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}
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}
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}
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sub find_ns{
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$ok=0;
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$res->usevc(0);
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$res->recurse(1);
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$res->nameservers($tld);
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print "Asking TLD Server $tld\n";
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$packet=$res->send($domain, 'NS');
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if ($packet){
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@additional_ns = $packet->additional;
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@answer_ns = $packet->answer;
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if (@additional_ns) {
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foreach $rr (@additional_ns) {
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$ns=$rr->rdatastr;
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if (get_dns()){$ok= 1;}
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}
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if ($ok){return 1;}
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}
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else {
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if (@answer_ns) {
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foreach $rr (@answer_ns) {
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$name=$rr->rdatastr;
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resolve_name();
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if (get_dns()){$ok= 1;}
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}
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if ($ok){return 1;}
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}
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else {return 0;}
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}
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}
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return 0;
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}
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sub get_dns(){
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$res->nameservers($ns);
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$res->usevc(0);
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print "Asking Name Server $ns\n";
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if ($version){get_ver();}
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$packet=$res->send($domain, 'NS');
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if ($packet){
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if ( get_axfr()){
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print " Zone Transfer succesful!\n";
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}
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else {
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get_any();
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get_activedir();
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if ($dig){dig_dns();}
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print "All possible information for $domain gathered!\n";
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}
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return 1;
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}
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else {return 0;}
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}
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sub get_ver{
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$res->usevc(0);
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print "\nChecking for DNS Server Version ...\n";
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$packet=$res->query('version.bind', 'TXT','CH');
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if ($res->errorstring eq "NOTIMP"){print "Microsoft DNS Server detected!\n";}
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if ($res->errorstring eq "FORMERR"){print "TinyDNS Server detected!\n";}
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if ($res->errorstring eq "NOERROR")
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{
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print "BIND DNS Server detected!\n";
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if ($packet) {
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@dnsversion = $packet->answer;
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if (@dnsversion) {
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foreach $rr (@dnsversion) {
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$ver=$rr->rdatastr;
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print "BIND Version: $ver \n";}
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}
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}
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}
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}
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sub get_any{
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print "\nGetting ANY DNS Record ...\n";
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$res->usevc(0);
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$packet=$res->query($domain, 'ANY');
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if ($packet) {
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$packet->print;
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print "\n----------------------------------------------------------------------\n\n";
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}
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@dnstypes=(
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"A",
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"AAAA",
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"AFSDB",
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"CERT",
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"CNAME",
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"DNAME",
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"EID",
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"HINFO",
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"ISDN",
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"LOC",
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"MB",
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"MG",
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"MINFO",
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"MR",
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"MX",
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"NAPTR",
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"NIMLOC",
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"NS",
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"NSAP",
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"NULL",
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"OPT",
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"PTR",
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"PX",
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"RP",
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"RT",
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"SOA",
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"TKEY",
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"TSIG",
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"TXT",
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"WKS",
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"X25"
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);
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foreach $i (@dnstypes) {
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print "\nTrying $i Record Type ...\n";
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$packet=$res->query($domain, $i);
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if ($packet) {
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$packet->print;
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print "\n----------------------------------------------------------------------\n\n";
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}
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}
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}
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sub get_activedir{
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print "\nLooking for Active Directory SRV Records ...\n";
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$res->usevc(0);
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@srvtype=(
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"_kerberos._tcp.Default-First-Site-Name._sites.dc._msdcs.",
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"_kerberos._tcp.Default-First-Site-Name._sites.",
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"_kerberos._tcp.dc._msdcs.",
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"_kerberos._tcp.",
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"_kerberos._udp.",
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"_kpasswd._tcp.",
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"_kpasswd._udp.",
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"_ldap._tcp.Default-First-Site-Name._sites.dc._msdcs.",
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"_ldap._tcp.Default-First-Site-Name._sites.gc._msdcs.",
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"_ldap._tcp.Default-First-Site-Name._sites.",
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"_ldap._tcp.dc._msdcs.",
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"_ldap._tcp.gc._msdcs.",
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"_ldap._tcp.pdc._msdcs.",
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"_ldap._tcp.",
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"_gc._tcp.Default-First-Site-Name._sites.",
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"_gc._tcp."
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);
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foreach $i (@srvtype) {
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$service = $i.$domain;
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print "\nTrying $service ...\n";
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$packet=$res->query($service, 'SRV');
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if ($packet) {
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$packet->print;
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print "\n----------------------------------------------------------------------\n\n";
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}
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}
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}
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sub dig_dns{
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print "\nStarting the DNS Digger ...\n";
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@hybridlst1=("0","1","2","3","4","5","6","7","8","9");
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@hybridlst2=("0","1","2","3","4","5","6","7","8","9");
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$res->usevc(0);
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if (open(NAMES,"names.txt")){
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while (<NAMES>){
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chomp($_);
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$host = $_.".".$domain;
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$packet=$res->query($host, 'ANY');
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if ($packet){
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$packet->print;
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print "\n----------------------------------------------------------------------\n\n";
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}
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if ($hybrid){
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foreach $h1 (@hybridlst1) {
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foreach $h2 (@hybridlst2) {
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$hybrid_host=$_.$h1.$h2.".".$domain;
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$packet=$res->query($hybrid_host, 'ANY');
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if ($packet){
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$packet->print;
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print "\n----------------------------------------------------------------------\n\n";
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}
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}
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}
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}
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if ($silent){sleep 1};
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}
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}
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else {print "Can't open names.txt!\n";}
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close(NAMES);
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}
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sub usage(){
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print "\nUsage: perl dnsdigger.pl <domain name> [OPTIONS]\n";
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print "-----------------------------------------------------------\n";
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print "OPTIONS:\n";
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print "silent : Activates a time loop of 1 second in the DNS Digger function\n";
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print "debug : Starts a debug output\n";
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print "nodig : Disable the Digger\n";
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print "port53 : Use Port 53 as Source Port\n";
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print "host : Use a specific DNS Server and must be followed by the IP Address\n";
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print "hybrid : Appends 01 to 99 to the names while digging\n";
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print "version: Try to get the DNS Server Version\n";
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print "\nEXAMPLES:\n";
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print "perl dnsdigger.pl example.com\n";
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print "perl dnsdigger.pl example.com silent\n";
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print "perl dnsdigger.pl example.com debug\n";
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print "perl dnsdigger.pl example.com host 10.1.1.1\n";
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exit;
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}
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# Main Programm
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if (@ARGV==0){usage();}
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$dig=1;
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$root=1;
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$version=0;
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print "\n";
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print "DNSDigger 0.3beta (c) 2003 by Michael Thumann (mthumann\@ernw.de)\n";
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print "----------------------------------------------------------------------\n\n";
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$res = Net::DNS::Resolver->new;
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$res->tcp_timeout(5);
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$res->udp_timeout(5);
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$res->retry(2);
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$res->retrans(3);
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if (@ARGV==1){
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$domain=$ARGV[0];
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if (find_rootserver()){print "Done.\n";}
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else{print "Error: Can't connect to the DNS Server!\n";}
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}
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if (@ARGV>=2){
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$domain=$ARGV[0];
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for ($o=1;$o<=@ARGV;$o++){
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$option=$ARGV[$o];
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if ($option eq "silent") {$silent=1;print "Time Loop enabled!\n"}
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if ($option eq "debug") {$res->debug(1);print "Debug enabled!\n";}
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if ($option eq "port53") {$res->srcport(53);print "Switching to Source Port 53!\n";}
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if ($option eq "nodig") {$dig=0;print "Digger disabled!\n";}
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if ($option eq "version") {$version=1;print "Query DNS Server Version enabled!\n";}
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if ($option eq "hybrid") {$hybrid=1;print "Hybrid Mode for Digger enabled!\n";}
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if ($option eq "host") {
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$root=0;
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print "Use specific DNS Server!\n";
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$ns=$ARGV[$o+1];
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}
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}
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if ($root){
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if (find_rootserver()){print "Done.\n";}
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else{print "Error: Can't connect to the DNS Server!\n";}
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}
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else{
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if (get_dns()){print "Done.\n";}
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else{print "Error: Can't connect to the DNS Server!\n";}
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}
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}
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# end
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319
dns/dnsdigger/names.txt
Normal file
319
dns/dnsdigger/names.txt
Normal file
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@ -0,0 +1,319 @@
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ILMI
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academico
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acceso
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access
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acid
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admin
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admins
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administracion
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administrador
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afiliados
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agenda
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agent
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aix
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alerts
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antivirus
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app
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apps
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appserver
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archie
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as400
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auto
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ayuda
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backup
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banking
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bbs
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bbdd
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bea
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beta
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bolsa
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buscador
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ca
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canal
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catalog
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certify
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cgi
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channel
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channels
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chat
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chats
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cisco
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clientes
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club
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cluster
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clusters
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code
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commerce
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community
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compaq
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compras
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consola
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console
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consumer
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contact
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contracts
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corporate
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correo
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correoweb
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cortafuegos
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cso
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data
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datos
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db
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db2
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default
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demo
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desarrollo
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descargas
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design
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dev
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||||||
|
develop
|
||||||
|
developer
|
||||||
|
device
|
||||||
|
dial
|
||||||
|
digital
|
||||||
|
dilbert
|
||||||
|
directory
|
||||||
|
disc
|
||||||
|
discovery
|
||||||
|
disk
|
||||||
|
disney
|
||||||
|
dns
|
||||||
|
dns1
|
||||||
|
dns2
|
||||||
|
dns3
|
||||||
|
dns-2
|
||||||
|
docs
|
||||||
|
documentos
|
||||||
|
documentacion
|
||||||
|
domain
|
||||||
|
domains
|
||||||
|
dominio
|
||||||
|
domino
|
||||||
|
dominoweb
|
||||||
|
download
|
||||||
|
earth
|
||||||
|
ecommerce
|
||||||
|
e-commerce
|
||||||
|
edi
|
||||||
|
education
|
||||||
|
ejemplo
|
||||||
|
email
|
||||||
|
empresa
|
||||||
|
empresas
|
||||||
|
enable
|
||||||
|
engine
|
||||||
|
engineer
|
||||||
|
enterprise
|
||||||
|
estadisticas
|
||||||
|
events
|
||||||
|
example
|
||||||
|
exchange
|
||||||
|
extern
|
||||||
|
external
|
||||||
|
extranet
|
||||||
|
fax
|
||||||
|
field
|
||||||
|
firewall
|
||||||
|
formacion
|
||||||
|
foro
|
||||||
|
foros
|
||||||
|
forum
|
||||||
|
forums
|
||||||
|
foto
|
||||||
|
fotos
|
||||||
|
fsp
|
||||||
|
ftp
|
||||||
|
ftp2
|
||||||
|
fw
|
||||||
|
fw1
|
||||||
|
fw-1
|
||||||
|
galeria
|
||||||
|
galerias
|
||||||
|
galleries
|
||||||
|
games
|
||||||
|
gateway
|
||||||
|
gopher
|
||||||
|
guest
|
||||||
|
gw
|
||||||
|
hello
|
||||||
|
help
|
||||||
|
helpdesk
|
||||||
|
helponline
|
||||||
|
hp
|
||||||
|
ibm
|
||||||
|
ibmdb
|
||||||
|
ids
|
||||||
|
images
|
||||||
|
imap
|
||||||
|
imap4
|
||||||
|
img
|
||||||
|
info
|
||||||
|
intern
|
||||||
|
internal
|
||||||
|
intranet
|
||||||
|
invalid
|
||||||
|
ipsec
|
||||||
|
ipsec-gw
|
||||||
|
irc
|
||||||
|
ircserver
|
||||||
|
jobs
|
||||||
|
juegos
|
||||||
|
ldap
|
||||||
|
link
|
||||||
|
linux
|
||||||
|
lista
|
||||||
|
lists
|
||||||
|
listserver
|
||||||
|
localhost
|
||||||
|
log
|
||||||
|
login
|
||||||
|
lotus
|
||||||
|
mail
|
||||||
|
mailhost
|
||||||
|
management
|
||||||
|
manager
|
||||||
|
map
|
||||||
|
maps
|
||||||
|
mapas
|
||||||
|
marketing
|
||||||
|
media
|
||||||
|
members
|
||||||
|
messenger
|
||||||
|
mngt
|
||||||
|
mobile
|
||||||
|
monitor
|
||||||
|
mrtg
|
||||||
|
multimedia
|
||||||
|
music
|
||||||
|
names
|
||||||
|
netdata
|
||||||
|
netstats
|
||||||
|
network
|
||||||
|
news
|
||||||
|
nms
|
||||||
|
nntp
|
||||||
|
nombres
|
||||||
|
noticias
|
||||||
|
ns
|
||||||
|
ns1
|
||||||
|
ns2
|
||||||
|
ntp
|
||||||
|
online
|
||||||
|
openview
|
||||||
|
outlook
|
||||||
|
oracle
|
||||||
|
page
|
||||||
|
pages
|
||||||
|
paginas
|
||||||
|
partner
|
||||||
|
partners
|
||||||
|
pda
|
||||||
|
personal
|
||||||
|
ph
|
||||||
|
pictures
|
||||||
|
pix
|
||||||
|
pop
|
||||||
|
pop3
|
||||||
|
portal
|
||||||
|
postales
|
||||||
|
prensa
|
||||||
|
press
|
||||||
|
private
|
||||||
|
proxy
|
||||||
|
prueba
|
||||||
|
pruebas
|
||||||
|
project
|
||||||
|
projects
|
||||||
|
public
|
||||||
|
ra
|
||||||
|
radio
|
||||||
|
raptor
|
||||||
|
ras
|
||||||
|
read
|
||||||
|
register
|
||||||
|
registro
|
||||||
|
remote
|
||||||
|
reports
|
||||||
|
resumenes
|
||||||
|
root
|
||||||
|
router
|
||||||
|
rwhois
|
||||||
|
sac
|
||||||
|
schedules
|
||||||
|
scotty
|
||||||
|
search
|
||||||
|
secret
|
||||||
|
secure
|
||||||
|
security
|
||||||
|
seri
|
||||||
|
serv
|
||||||
|
serv2
|
||||||
|
server
|
||||||
|
service
|
||||||
|
services
|
||||||
|
servicio
|
||||||
|
servidor
|
||||||
|
shop
|
||||||
|
shopping
|
||||||
|
site
|
||||||
|
sms
|
||||||
|
smtp
|
||||||
|
smtphost
|
||||||
|
snmp
|
||||||
|
snmpd
|
||||||
|
snort
|
||||||
|
solaris
|
||||||
|
solutions
|
||||||
|
soporte
|
||||||
|
source
|
||||||
|
sql
|
||||||
|
ssl
|
||||||
|
stats
|
||||||
|
store
|
||||||
|
streaming
|
||||||
|
sun
|
||||||
|
support
|
||||||
|
switch
|
||||||
|
sysback
|
||||||
|
system
|
||||||
|
tech
|
||||||
|
terminal
|
||||||
|
test
|
||||||
|
tienda
|
||||||
|
time
|
||||||
|
tivoli
|
||||||
|
transfers
|
||||||
|
training
|
||||||
|
uddi
|
||||||
|
update
|
||||||
|
video
|
||||||
|
vpn
|
||||||
|
wais
|
||||||
|
wap
|
||||||
|
web
|
||||||
|
webdocs
|
||||||
|
weblib
|
||||||
|
weblogic
|
||||||
|
webmail
|
||||||
|
webserver
|
||||||
|
webservices
|
||||||
|
websphere
|
||||||
|
whois
|
||||||
|
wireless
|
||||||
|
work
|
||||||
|
world
|
||||||
|
write
|
||||||
|
w1
|
||||||
|
w2
|
||||||
|
w3
|
||||||
|
ws
|
||||||
|
ws1
|
||||||
|
ws2
|
||||||
|
ws3
|
||||||
|
www
|
||||||
|
www1
|
||||||
|
www2
|
||||||
|
www3
|
||||||
|
|
||||||
|
|
||||||
41
dns/dnsdigger/readme.txt
Normal file
41
dns/dnsdigger/readme.txt
Normal file
|
|
@ -0,0 +1,41 @@
|
||||||
|
DNSDigger is a programm to gather as much as possible informations from DNS Servers. Two different methods are use:
|
||||||
|
|
||||||
|
1. DNS Server Query
|
||||||
|
Query every DNS Server that is responsible for the domain, primary and each secondary. Sometimes only one DNS Server is misconfigured, but that could be enough to get the whole zone file or a provider DNS is used. Some providers allow zone transfers from their DNS Servers.
|
||||||
|
|
||||||
|
2. DNS Digging
|
||||||
|
The idea is to use the same technique as with password attacks based on dictionaries to find hostnames hidden in the DNS zone.There's a names.txt which contains the dictionary. The option HYBRID will append the nummbers 01 to 99 to each entry in the names.txt to uncover additional hostnames.
|
||||||
|
|
||||||
|
3. DNS Server Version
|
||||||
|
DNSDigger uses a chaos class query to find out which DNS Server is running. Microsoft DNS Server and TinyDNS answer with a very special error message and BIND responds with it's version, if not configured to fake the information.
|
||||||
|
|
||||||
|
4. Active Directory
|
||||||
|
DNSdigger queries the common SRV records for windows 2000 domain controllers to identify them.
|
||||||
|
|
||||||
|
The tools might be useful for all pen-testers that have to gather DNS informations during a pen-test.
|
||||||
|
|
||||||
|
The program is in beta state, so there might be bugs. If you find some please report them to mthumann@ernw.de
|
||||||
|
|
||||||
|
You need the NET::DNS Module from Michael Fuhr to run the program. You can download it from the original website
|
||||||
|
http://www.net-dns.org
|
||||||
|
or from activestate for ActivePerl
|
||||||
|
http://ppm.activestate.com/PPMPackages/zips/6xx-builds-only/Net-DNS-0.34.zip
|
||||||
|
|
||||||
|
For resolving dns names enter the ip address of your favorite dns server in the file dns-server.dat
|
||||||
|
|
||||||
|
Known bugs:
|
||||||
|
None so far ;-))
|
||||||
|
|
||||||
|
License:
|
||||||
|
Copyright (c) 2003 Michael Thumann.
|
||||||
|
You can use and distribute the program for free as long as the code is not modified.
|
||||||
|
|
||||||
|
Disclaimer:
|
||||||
|
The program is provided "AS IS" without warranty
|
||||||
|
of any kind. In no event shall the author be liable for any damages
|
||||||
|
whatsoever including direct, indirect, incidental, consequential,
|
||||||
|
loss of business profits or special damages due to the misuse of this
|
||||||
|
program.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
13
dns/dnsdigger/root-servers.dat
Normal file
13
dns/dnsdigger/root-servers.dat
Normal file
|
|
@ -0,0 +1,13 @@
|
||||||
|
198.41.0.4
|
||||||
|
128.9.0.107
|
||||||
|
192.33.4.12
|
||||||
|
128.8.10.90
|
||||||
|
192.203.230.10
|
||||||
|
192.5.5.241
|
||||||
|
192.112.36.4
|
||||||
|
128.63.2.53
|
||||||
|
192.36.148.17
|
||||||
|
192.58.128.30
|
||||||
|
193.0.14.129
|
||||||
|
198.32.64.12
|
||||||
|
202.12.27.33
|
||||||
164
dns/dnswalk/CHANGES
Normal file
164
dns/dnswalk/CHANGES
Normal file
|
|
@ -0,0 +1,164 @@
|
||||||
|
$Id: CHANGES,v 1.11 1997/10/06 13:27:37 barr Exp barr $
|
||||||
|
|
||||||
|
Version 2.0.2
|
||||||
|
|
||||||
|
Silly bug in output, SOA= was listing the domain, not the master.
|
||||||
|
Reported by Jeff Miller <jmiller@smart.net>.
|
||||||
|
|
||||||
|
dnswalk now checks to see that target of MX, CNAME and NS are a hostname,
|
||||||
|
not an IP addr.
|
||||||
|
|
||||||
|
Version 2.0.1
|
||||||
|
|
||||||
|
Regexp bug in 'makereports' script. (chopped off last charcter of
|
||||||
|
contact address).
|
||||||
|
|
||||||
|
Version 2.0.0 (beta)
|
||||||
|
|
||||||
|
Ported to Net::DNS. Now no longer relies on 'dig'. Some less-used
|
||||||
|
error messages removed, such as the 'double domain' check.
|
||||||
|
|
||||||
|
dnswalk now no longer saves zone transferrs to local files, due to
|
||||||
|
the fact that dnswalk no longer uses 'dig'. The zone transfer itself
|
||||||
|
doesn't take that long -- mostly it's CPU time churning on what comes
|
||||||
|
in. I may add it back if there's enough demand (using the "Storage"
|
||||||
|
perl package, like what is used by the Net::DNS package's examples)
|
||||||
|
|
||||||
|
Added 'WARN', 'FAIL', and 'BAD' prefixes to error messages, to indicate
|
||||||
|
some level of 'badness' associated with a particular message. Makes
|
||||||
|
machine parsing easier, as well as human interpreting. ('FAIL'
|
||||||
|
was called 'ERROR' before beta release).
|
||||||
|
|
||||||
|
dnswalk now exits with a return code equal to the number of 'BAD' things
|
||||||
|
found. (from an request by Dave Crocker)
|
||||||
|
|
||||||
|
dnswalk (with -F fascist checking) no longer gives A record warnings
|
||||||
|
with hosts like "neptune" and "neptune-le0" (it treats them as the
|
||||||
|
same host). Formerly it would warn that A record for neptune-le0
|
||||||
|
"points to" neptune. (this is a common situation with multi-homed
|
||||||
|
hosts, where A records pointing just to individual interfaces are used).
|
||||||
|
Anything "host-something" is treated the same as "host". (request
|
||||||
|
from David Nelson <dnelson@iphase.com>)
|
||||||
|
|
||||||
|
perform some rudimentary checks on SOA contact field. (99% of
|
||||||
|
the time the error is someone forgetting you have to replace the
|
||||||
|
"@" sign in the email address with a ".".)
|
||||||
|
|
||||||
|
Reformatted the code to be a bit more readable.
|
||||||
|
|
||||||
|
Version 1.8.3
|
||||||
|
Miscellaneous fixes, getautservers(). Condensed code.
|
||||||
|
|
||||||
|
Hack added to ignore RFC 1101 netmasks encoding.
|
||||||
|
|
||||||
|
Assigning $1 wasn't working, use local variable. Patch from Mark
|
||||||
|
Andrews <Mark.Andrews@dms.csiro.au>.
|
||||||
|
|
||||||
|
New Perl script "makereports" included to take output and generate
|
||||||
|
reports for each hostmaster for the problems within his/her zone.
|
||||||
|
|
||||||
|
Suggestion by marka@syd.dms.CSIRO.AU (Mark Andrews) to only
|
||||||
|
check for invalid characters on A or MX records. I could probably
|
||||||
|
do two-level checking, one for 1033 compliance on all records
|
||||||
|
and 1035 compliance on mail-able names (A and MX). However
|
||||||
|
this is a reasonable compromise for now.
|
||||||
|
|
||||||
|
Version 1.8.2
|
||||||
|
Fixed spelling errors and shoddy syntax in getauthservers(), from
|
||||||
|
Jost Krieger <Jost.Krieger@rz.ruhr-uni-bochum.de>
|
||||||
|
|
||||||
|
Accounted for Solaris's broken gethostbyname() which includes trailing
|
||||||
|
dots in retuned name.
|
||||||
|
|
||||||
|
Minor fixes in lame delegation checking, and getauthservers().
|
||||||
|
|
||||||
|
Version 1.8.1
|
||||||
|
One-line fix to remove reference to non-existent parameter to getmaster().
|
||||||
|
Reported by petri@ibr.cs.tu-bs.de (Stefan Petri).
|
||||||
|
|
||||||
|
Version 1.8
|
||||||
|
Typos, documentation corrections, additions to TIPS as well as
|
||||||
|
stuff for TODO from Piete Brooks <Piete.Brooks@cl.cam.ac.uk>.
|
||||||
|
|
||||||
|
Patch from Thorsten Lockert <tholo@sigmasoft.com>: remove directory
|
||||||
|
if zone transfer fails.
|
||||||
|
|
||||||
|
Fixed getauthservers() routine. Sometimes had list of servers
|
||||||
|
which contained each server listed twice. Also fixed it to
|
||||||
|
use the 'master server' field of the SOA record as a 'hint'
|
||||||
|
to which server to check first.
|
||||||
|
|
||||||
|
Fixed typo in dot-death checking. Error message forgot \n.
|
||||||
|
|
||||||
|
Added -D flag to set base directory for saved axfr files.
|
||||||
|
|
||||||
|
Version 1.7
|
||||||
|
Added "_" to list of invalid characters in a hostname. (Painful
|
||||||
|
because we have hundreds of PCs and Macs here with one.) Can
|
||||||
|
now be supressed with '-i' option (whew).
|
||||||
|
|
||||||
|
Fixed wildcard RR's being marked as having invalid characters.
|
||||||
|
(Thanks to Paul Turner <turner@telstar.kodak.com> for reporting it)
|
||||||
|
|
||||||
|
Changed how the return codes for gethostby*() routines were being
|
||||||
|
checked. Added caveat in README about herror(). Thanks to Bill Fenner
|
||||||
|
|
||||||
|
Suppresses duplicate error message per zone. Idea from Paul Turner.
|
||||||
|
|
||||||
|
Checks for dom.ain.dom.ain. in data, in case someone forgot the
|
||||||
|
trailing '.'.
|
||||||
|
|
||||||
|
Finally added a man page. Trimmed out redundant information
|
||||||
|
from the README file.
|
||||||
|
|
||||||
|
Version 1.6
|
||||||
|
removed -c switch, since I thought it would work a long time ago, but
|
||||||
|
later found out it could never be made to work. Well, it could, just
|
||||||
|
not very nicely. (nor efficiently)
|
||||||
|
|
||||||
|
Fixed bug with parsing of dig output. Newer dig has slightly different
|
||||||
|
output, causing serial numbers to not be pulled out.
|
||||||
|
|
||||||
|
Changed the do-dnswalk script to use exec > logfile instead of
|
||||||
|
redirecting every invocation to a logfile. Idea from Dan Ehrlich.
|
||||||
|
|
||||||
|
Fixed problem with dnswalk using old list of subdomains in axfr file,
|
||||||
|
ignoring the new zone transfer if it was needed.
|
||||||
|
|
||||||
|
Accounted for annoying behavior of new dig to print duplicate SOA's.
|
||||||
|
|
||||||
|
Documented nameserver error reporting.
|
||||||
|
|
||||||
|
Version 1.5
|
||||||
|
|
||||||
|
added -F switch. This performs "fascist" checking. For every A record,
|
||||||
|
it checks to see that it actually points to the canonical name listed
|
||||||
|
for the PTR and reports mismatches. Try this switch at least once to see
|
||||||
|
what kind of things pop up. (You may be surprised)
|
||||||
|
|
||||||
|
added -m switch. Performs check on zone only if it has been modified
|
||||||
|
(serial number changed) since the previous run.
|
||||||
|
|
||||||
|
changed format of messages to be shorter and more precise. (and hopefully
|
||||||
|
easier to read) Read the README section for a full description.
|
||||||
|
|
||||||
|
warns if a zone has only one authoratative nameserver
|
||||||
|
*** in later versions of 1.3, not posted here, but available for ftp,
|
||||||
|
there was a bad bug which caused erroneous warnings about having only
|
||||||
|
one nameserver. (was using the wrong variable)
|
||||||
|
|
||||||
|
reports any errors listed in dig zone transfer output. (usually
|
||||||
|
caused by a corrupted zone file, or invalid syntax in data; for example
|
||||||
|
only one field in an HINFO record.)
|
||||||
|
|
||||||
|
now reports any resolver errors from gethostbyname and gethostbyaddr.
|
||||||
|
(for example, a server timeout, connection refused, etc)
|
||||||
|
|
||||||
|
sorts output by zone (correctly -- some versions of 1.3 didn't quite do
|
||||||
|
this right)
|
||||||
|
|
||||||
|
displays server of authority and zone contact for each zone it checks.
|
||||||
|
|
||||||
|
I've now included a 'do-dnswalk' script that is an example wrapper
|
||||||
|
that I use around dnswalk to turn on status debugging and put the
|
||||||
|
results in a log file. Salt to taste.
|
||||||
95
dns/dnswalk/README
Normal file
95
dns/dnswalk/README
Normal file
|
|
@ -0,0 +1,95 @@
|
||||||
|
dnswalk 2.0 - August 4, 1997
|
||||||
|
|
||||||
|
Author: David Barr <barr@cis.ohio-state.edu>
|
||||||
|
$Id: README,v 1.6 1997/08/04 19:09:34 barr Exp barr $
|
||||||
|
|
||||||
|
INTRO
|
||||||
|
|
||||||
|
dnswalk is a DNS debugger. It performs zone transfers of specified
|
||||||
|
domains, and checks the database in numerous ways for internal
|
||||||
|
consistency, as well as accuracy.
|
||||||
|
|
||||||
|
dnswalk requires perl and the Net::DNS Perl package. If you do not have
|
||||||
|
these, get them. (perl is assumed to be in /usr/local/bin, edit the first
|
||||||
|
line of dnswalk if it is not)
|
||||||
|
|
||||||
|
They can be found by at:
|
||||||
|
http://www.perl.com/perl/
|
||||||
|
|
||||||
|
dnswalk used to require 'dig' (part of the BIND distribution). However,
|
||||||
|
different versions of dig gave output which was ever so slightly different,
|
||||||
|
causing dnswalk to break. (This is usually easy to fix, even in a
|
||||||
|
backward-compatible fashion, but it was annoying nonetheless) Also,
|
||||||
|
using an external program made error checking more difficult and not
|
||||||
|
very reliable. Since error checking is the heart of what dnswalk is about,
|
||||||
|
this wasn't good. I finally got off my duff and ported dnswalk to Michael
|
||||||
|
Fuhr's Net::DNS package, something I've been wanting to do for a while.
|
||||||
|
(actually another reason I waited so long was the Net::DNS package wasn't
|
||||||
|
complete enough initially for for a complete port.)
|
||||||
|
|
||||||
|
|
||||||
|
dnswalk is not for the faint of heart. It should NOT be used
|
||||||
|
without a firm knowledge of the DNS RFC's. The warnings and errors
|
||||||
|
must be interpreted within the context they are being used. Something
|
||||||
|
may be flagged as a warning, but in reality it is a really bad error.
|
||||||
|
Conversely dnswalk will flag things as warnings and possibly even
|
||||||
|
errors, but they may actually be perfectly "legal" or normal in your
|
||||||
|
specific situation. dnswalk is not an AI engine. It just provides
|
||||||
|
useful information which you need to interpret. If you use this tool
|
||||||
|
for cracking or otherwise evil purposes, the author hereby considers
|
||||||
|
you a slime-ball. See the end of this README file for a list of good
|
||||||
|
reading material.
|
||||||
|
|
||||||
|
dnswalk is not a replacement for doc, although dnswalk is starting
|
||||||
|
to incorporate some of the things doc checks for. dnswalk was written to
|
||||||
|
check individual database entries, while 'doc' ensures that the overall
|
||||||
|
database structure and authority records are consistent. dnswalk may
|
||||||
|
not even function correctly (or find real problems) if authority records
|
||||||
|
are missing or incorrect.
|
||||||
|
|
||||||
|
This program may be freely distributed, as long as this notice
|
||||||
|
and documentation are distributed with the program. This program is
|
||||||
|
released as-is, with no warranty expressed or implied. Some assembly
|
||||||
|
required, contents may settle during shipment. This program can be
|
||||||
|
found at
|
||||||
|
|
||||||
|
http://www.cis.ohio-state.edu/~barr/dnswalk/
|
||||||
|
|
||||||
|
dnswalk tends to produce lots of output, so I'd suggest
|
||||||
|
redirecting this into a file of your choice. I debated using doc's
|
||||||
|
strategy of automatically putting it in a logfile, but decided not
|
||||||
|
to. (The author reserves the right to change his mind) For small,
|
||||||
|
mostly-correct domains it is pretty manageable, however. For larger
|
||||||
|
domains, use the included 'do-dnswalk' script as a guide.
|
||||||
|
|
||||||
|
Please refer to the man page on what dnswalk checks for, and
|
||||||
|
the format of the output.
|
||||||
|
|
||||||
|
*** NOTICE ***
|
||||||
|
I fully realize that while some of the rules are not in
|
||||||
|
violation of an RFC, it might be wise to reconsider their usage
|
||||||
|
anyway. dnswalk was written to be a tool to let the hostmaster decide
|
||||||
|
what are troublesome areas, not as a program that has all the answers.
|
||||||
|
*** NOTICE ***
|
||||||
|
|
||||||
|
This program was originally tested with data from the psu.edu domain.
|
||||||
|
If your site does things differently than the way we do things, then you
|
||||||
|
may see it report things as errors, when in fact they are "okay".
|
||||||
|
If you notice something not being reported, or something reported that
|
||||||
|
is not an error, please send me output! I fully admit that I'm not
|
||||||
|
an expert in DNS and the requirements. My rules tend to be skewed to
|
||||||
|
my personal feelings about what "nice" DNS databases look like. Others
|
||||||
|
are free to differ. (and tell me so)
|
||||||
|
|
||||||
|
Author:
|
||||||
|
David Barr <barr@cis.ohio-state.edu>
|
||||||
|
Lead System Administrator
|
||||||
|
The Ohio State University, Department of Computer and Information Science
|
||||||
|
|
||||||
|
Thanks:
|
||||||
|
|
||||||
|
Bill Fenner - tips with perl
|
||||||
|
Michael Fuhr - for writing Net::DNS!
|
||||||
|
Dave Crocker - for providing the spark necessary for me to pick up
|
||||||
|
developement of dnswalk-2.0 again.
|
||||||
|
|
||||||
18
dns/dnswalk/TODO
Normal file
18
dns/dnswalk/TODO
Normal file
|
|
@ -0,0 +1,18 @@
|
||||||
|
replace remaining gethostby*() calls with Net::DNS calls. (better
|
||||||
|
error reporting)
|
||||||
|
|
||||||
|
compare serial number of zone transfer data and report differences
|
||||||
|
|
||||||
|
Check RP records that they point to a TXT record.
|
||||||
|
|
||||||
|
Check for CNAME and other data. (modern BIND versions disallow this,
|
||||||
|
but not everyone sadly is up to date)
|
||||||
|
|
||||||
|
Check parent delegation (a la doc) and check for lame delegations.
|
||||||
|
Compare serial numbers of all NS servers and report differences.
|
||||||
|
(a la doc)
|
||||||
|
|
||||||
|
./dnswalk non-existant.domain doesn't generate a very useful message
|
||||||
|
|
||||||
|
complete RFC 1101 check.. A records in rev file
|
||||||
|
|
||||||
414
dns/dnswalk/dnswalk
Executable file
414
dns/dnswalk/dnswalk
Executable file
|
|
@ -0,0 +1,414 @@
|
||||||
|
#!/usr/contrib/bin/perl
|
||||||
|
#
|
||||||
|
# dnswalk Walk through a DNS tree, pulling out zone data and
|
||||||
|
# dumping it in a directory tree
|
||||||
|
#
|
||||||
|
# $Id: dnswalk,v 1.18 1997/10/06 13:23:58 barr Exp barr $
|
||||||
|
#
|
||||||
|
# check data collected for legality using standard resolver
|
||||||
|
#
|
||||||
|
# invoke as dnswalk domain > logfile
|
||||||
|
# Options:
|
||||||
|
# -r Recursively descend subdomains of domain
|
||||||
|
# -i Suppress check for invalid characters in a domain name.
|
||||||
|
# -a turn on warning of duplicate A records.
|
||||||
|
# -d Debugging
|
||||||
|
# -m Check only if the domain has been modified. (Useful only if
|
||||||
|
# dnswalk has been run previously.)
|
||||||
|
# -F Enable "facist" checking. (See man page)
|
||||||
|
# -l Check lame delegations
|
||||||
|
|
||||||
|
use Getopt::Std;
|
||||||
|
use IO::Socket;
|
||||||
|
use Net::DNS;
|
||||||
|
|
||||||
|
getopts("D:rfiadmFl");
|
||||||
|
|
||||||
|
$num_error{'FAIL'}=0; # failures to access data
|
||||||
|
$num_error{'WARN'}=0; # questionable data
|
||||||
|
$num_error{'BAD'}=0; # bad data
|
||||||
|
|
||||||
|
# Where all zone transfer information is saved. You can change this to
|
||||||
|
# something like /tmp/dnswalk if you don't want to clutter up the current
|
||||||
|
# directory
|
||||||
|
if ($opt_D) {
|
||||||
|
$basedir = $opt_D;
|
||||||
|
} else {
|
||||||
|
$basedir = ".";
|
||||||
|
}
|
||||||
|
($domain = $ARGV[0]) =~ tr/A-Z/a-z/;
|
||||||
|
if ($domain !~ /\.$/) {
|
||||||
|
die "Usage: dnswalk domain\ndomain MUST end with a '.'\n";
|
||||||
|
}
|
||||||
|
if (! -d $basedir) {
|
||||||
|
mkdir($basedir,0777) || die "FAIL: Cannot create $basedir: $!\n";
|
||||||
|
}
|
||||||
|
|
||||||
|
&dowalk($domain);
|
||||||
|
print STDERR "$num_error{'FAIL'} failures, $num_error{'WARN'} warnings, $num_error{'BAD'} errors.\n";
|
||||||
|
exit $num_error{'BAD'};
|
||||||
|
|
||||||
|
sub dowalk {
|
||||||
|
my (@subdoms);
|
||||||
|
my (@sortdoms);
|
||||||
|
my ($domain)=$_[0];
|
||||||
|
$modified=0;
|
||||||
|
return unless $domain;
|
||||||
|
print "Checking $domain\n";
|
||||||
|
@subdoms=&doaxfr($domain);
|
||||||
|
&check_zone($domain) if (defined(@zone) && @zone);
|
||||||
|
undef @zone;
|
||||||
|
return if (!(defined(@subdoms) && @subdoms));
|
||||||
|
@sortdoms = sort byhostname @subdoms;
|
||||||
|
local ($subdom);
|
||||||
|
if ($opt_r) {
|
||||||
|
foreach $subdom (@sortdoms) {
|
||||||
|
&dowalk($subdom);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
# try to get a zone transfer, trying each listed authoritative server if
|
||||||
|
# if fails.
|
||||||
|
sub doaxfr {
|
||||||
|
local ($domain)=@_[0];
|
||||||
|
local (%subdoms)=();
|
||||||
|
local ($subdom);
|
||||||
|
local(@servers) = &getauthservers($domain);
|
||||||
|
&printerr("BAD", "$domain has only one authoritative nameserver\n")
|
||||||
|
if (scalar(@servers) == 1);
|
||||||
|
&printerr("BAD", "$domain has NO authoritative nameservers!\n")
|
||||||
|
if (scalar(@servers) == 0);
|
||||||
|
SERVER:
|
||||||
|
foreach $server (@servers) {
|
||||||
|
print STDERR "Getting zone transfer of $domain from $server...";
|
||||||
|
my $res = new Net::DNS::Resolver;
|
||||||
|
$res->nameservers($server);
|
||||||
|
@zone=$res->axfr($domain);
|
||||||
|
unless (defined(@zone) && @zone) {
|
||||||
|
print STDERR "failed\n";
|
||||||
|
&printerr("FAIL",
|
||||||
|
"Zone transfer of $domain from $server failed: ".
|
||||||
|
$res->errorstring. "\n");
|
||||||
|
next SERVER;
|
||||||
|
}
|
||||||
|
@subdoms=undef;
|
||||||
|
foreach $rr (@zone) {
|
||||||
|
if ($rr->type eq "NS") {
|
||||||
|
$subdom = $rr->name;
|
||||||
|
$subdom =~ tr/A-Z/a-z/;
|
||||||
|
if ((!&equal($subdom,$domain)) && ( !$subdoms{$subdom})) {
|
||||||
|
$subdoms{$subdom}=1;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
print STDERR "done.\n";
|
||||||
|
last SERVER;
|
||||||
|
} # foreach #
|
||||||
|
unless (defined(@zone) && @zone) {
|
||||||
|
&printerr("BAD","All zone transfer attempts of $domain failed!\n");
|
||||||
|
return undef;
|
||||||
|
}
|
||||||
|
return (keys %subdoms);
|
||||||
|
}
|
||||||
|
|
||||||
|
sub getauthservers {
|
||||||
|
my ($domain)=$_[0];
|
||||||
|
my ($master)=&getmaster($domain);
|
||||||
|
my ($foundmaster)=0;
|
||||||
|
my ($ns);
|
||||||
|
my ($ns_tmp);
|
||||||
|
my ($res);
|
||||||
|
my ($ns_req);
|
||||||
|
my (@servers);
|
||||||
|
my (%servhash);
|
||||||
|
return if (!$master); # this is null if there is no SOA or not found
|
||||||
|
return if (!$domain);
|
||||||
|
$res = new Net::DNS::Resolver;
|
||||||
|
$ns_req = $res->query($domain, "NS");
|
||||||
|
&printerr("FAIL", "No nameservers found for $domain: ".
|
||||||
|
$res->errorstring ."\n")
|
||||||
|
unless (defined($ns_req) and ($ns_req->header->ancount > 0));
|
||||||
|
foreach $ns ($ns_req->answer) {
|
||||||
|
$ns_tmp = $ns->nsdname;
|
||||||
|
$ns_tmp =~ tr/A-Z/a-z/;
|
||||||
|
if (&equal($ns_tmp,$master)) {
|
||||||
|
$foundmaster=1; # make sure the master is at the top
|
||||||
|
} else {
|
||||||
|
push(@servers,$ns_tmp) if ($servhash{$ns_tmp}++<1);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
if ($foundmaster) {
|
||||||
|
unshift(@servers,$master);
|
||||||
|
}
|
||||||
|
return @servers;
|
||||||
|
}
|
||||||
|
|
||||||
|
# return 'master' server for zone
|
||||||
|
sub getmaster {
|
||||||
|
my ($zone)=$_[0];
|
||||||
|
my ($res) = new Net::DNS::Resolver;
|
||||||
|
my ($packet) = new Net::DNS::Packet($zone, "SOA", "IN");
|
||||||
|
my ($soa_req) = $res->send($packet);
|
||||||
|
unless (defined($soa_req)) {
|
||||||
|
&printerr("FAIL", "Cannot get SOA record for $zone:".
|
||||||
|
$res->errorstring ."\n");
|
||||||
|
return "";
|
||||||
|
}
|
||||||
|
unless (($soa_req->header->ancount >= 1) &&
|
||||||
|
(($soa_req->answer)[0]->type eq "SOA")) {
|
||||||
|
&printerr("BAD", "SOA record not found for $zone\n");
|
||||||
|
return "";
|
||||||
|
}
|
||||||
|
return ($soa_req->answer)[0]->mname;
|
||||||
|
}
|
||||||
|
|
||||||
|
# open result of zone tranfer and check lots of nasty things
|
||||||
|
# here's where the fun begins
|
||||||
|
sub check_zone {
|
||||||
|
my ($domain)=$_[0];
|
||||||
|
local (%glues)=(); # look for duplicate glue (A) records
|
||||||
|
local ($name, $aliases, $addrtype, $length, @addrs);
|
||||||
|
local ($prio,$mx);
|
||||||
|
local ($soa,$contact);
|
||||||
|
local ($lastns); # last NS record we saw
|
||||||
|
local (@keys); # temp variable
|
||||||
|
foreach $rr (@zone) {
|
||||||
|
# complain about invalid chars only for mail names
|
||||||
|
if ((($rr->type eq "A") || ($rr->type eq "MX")) && (!$opt_i) &&
|
||||||
|
($rr->name =~ /[^\*][^-A-Za-z0-9.]/)) {
|
||||||
|
&printerr("WARN", $rr->name .": invalid character(s) in name\n");
|
||||||
|
}
|
||||||
|
if ($rr->type eq "SOA") {
|
||||||
|
print STDERR 's' if $opt_d;
|
||||||
|
print "SOA=". $rr->mname ." contact=". $rr->rname ."\n";
|
||||||
|
# basic address check. No "@", and user.dom.ain (two or more dots)
|
||||||
|
if (($rr->rname =~ /@/)||!($rr->rname =~ /\..*\./)) {
|
||||||
|
&printerr("WARN", "SOA contact name (".
|
||||||
|
$rr->rname .") is invalid\n");
|
||||||
|
}
|
||||||
|
} elsif ($rr->type eq "PTR") {
|
||||||
|
print STDERR 'p' if $opt_d;
|
||||||
|
if (scalar((@keys=split(/\./,$rr->name))) == 6 ) {
|
||||||
|
# check if forward name exists, but only if reverse is
|
||||||
|
# a full IP addr
|
||||||
|
# skip ".0" networks
|
||||||
|
if ($keys[0] ne "0") {
|
||||||
|
($name, $aliases, $addrtype, $length,
|
||||||
|
@addrs)=gethostbyname($rr->ptrdname);
|
||||||
|
# if (!(($name, $aliases, $addrtype, $length,
|
||||||
|
# @addrs)=gethostbyname($rr->ptrdname))) {
|
||||||
|
# &printerr("FAIL", "gethostbyname(".
|
||||||
|
# $rr->ptrdname ."): $!\n");
|
||||||
|
# }
|
||||||
|
# else {
|
||||||
|
if (!$name) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." PTR ". $rr->ptrdname .": unknown host\n");
|
||||||
|
}
|
||||||
|
elsif (!&equal($name,$rr->ptrdname)) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." PTR ". $rr->ptrdname .": CNAME (to $name)\n");
|
||||||
|
}
|
||||||
|
elsif (!&matchaddrlist($rr->name)) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." PTR ". $rr->ptrdname .": A record not found\n");
|
||||||
|
}
|
||||||
|
# }
|
||||||
|
}
|
||||||
|
}
|
||||||
|
} elsif (($rr->type eq "A") ) {
|
||||||
|
print STDERR 'a' if $opt_d;
|
||||||
|
# check to see that a reverse PTR record exists
|
||||||
|
($name,$aliases,$addrtype,$length,@addrs)=gethostbyaddr(pack('C4',
|
||||||
|
split(/\./,$rr->address)),2);
|
||||||
|
if (!$name) {
|
||||||
|
# hack - allow RFC 1101 netmasks encoding
|
||||||
|
if ($rr->address !=~ /^255/) {
|
||||||
|
&printerr("WARN", $rr->name ." A ".
|
||||||
|
$rr->address .": no PTR record\n");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
elsif ($opt_F && !&equal($name,$rr->name)) {
|
||||||
|
# Filter out "hostname-something" (like "neptune-le0")
|
||||||
|
if (index(split (/\./, $rr->name, 2) . "-",
|
||||||
|
split (/\./, $name, 2)) == -1 ) {
|
||||||
|
&printerr("WARN", $rr->name ." A ".
|
||||||
|
$rr->address .": points to $name\n")
|
||||||
|
if ((split(/\./,$name))[0] ne "localhost");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
if ($main'opt_a) {
|
||||||
|
# keep list in %glues, report any duplicates
|
||||||
|
if ($glues{$rr->address} eq "") {
|
||||||
|
$glues{$rr->address}=$rr->name;
|
||||||
|
}
|
||||||
|
elsif (($glues{$rr->address} eq $rr->name) &&
|
||||||
|
(!&equal($lastns,$domain))) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
.": possible duplicate A record (glue of $lastns?)\n");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
} elsif ($rr->type eq "NS") {
|
||||||
|
$lastns=$rr->name;
|
||||||
|
print STDERR 'n' if $opt_d;
|
||||||
|
# check to see if object of NS is real
|
||||||
|
&checklamer($rr->name,$rr->nsdname) if ($main'opt_l);
|
||||||
|
# check for bogusnesses like NS->IP addr
|
||||||
|
if (&isipv4addr($rr->nsdname)) {
|
||||||
|
&printerr("BAD", $rr->name
|
||||||
|
." NS ". $rr->nsdname .": Nameserver must be a hostname\n");
|
||||||
|
}
|
||||||
|
($name, $aliases, $addrtype, $length,
|
||||||
|
@addrs)=gethostbyname($rr->nsdname);
|
||||||
|
# if (!(($name, $aliases, $addrtype, $length,
|
||||||
|
# @addrs)=gethostbyname($rr->nsdname))) {
|
||||||
|
# &printerr("FAIL", "gethostbyname(". $rr->nsdname ."): $!\n");
|
||||||
|
# }
|
||||||
|
# else {
|
||||||
|
if (!$name) {
|
||||||
|
&printerr("BAD", $rr->name
|
||||||
|
." NS ". $rr->nsdname .": unknown host\n");
|
||||||
|
} elsif (!&equal($name,$rr->nsdname)) {
|
||||||
|
&printerr("BAD", $rr->name
|
||||||
|
." NS ". $rr->nsdname .": CNAME (to $name)\n");
|
||||||
|
}
|
||||||
|
# }
|
||||||
|
} elsif ($rr->type eq "MX") {
|
||||||
|
print STDERR 'm' if $opt_d;
|
||||||
|
# check to see if object of mx is real
|
||||||
|
if (&isipv4addr($rr->exchange)) {
|
||||||
|
&printerr("BAD", $rr->name
|
||||||
|
." MX ". $rr->exchange .": Mail exchange must be a hostname\n");
|
||||||
|
}
|
||||||
|
($name, $aliases, $addrtype, $length,
|
||||||
|
@addrs)=gethostbyname($rr->exchange);
|
||||||
|
# if (!(($name, $aliases, $addrtype, $length,
|
||||||
|
# @addrs)=gethostbyname($rr->exchange))) {
|
||||||
|
# &printerr("FAIL", "gethostbyname(". $rr->exchange ."): $!\n");
|
||||||
|
# }
|
||||||
|
# else {
|
||||||
|
if (!$name) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." MX ". $rr->exchange .": unknown host\n");
|
||||||
|
}
|
||||||
|
elsif (!&equal($name,$rr->exchange)) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." MX ". $rr->exchange .": CNAME (to $name)\n");
|
||||||
|
}
|
||||||
|
# }
|
||||||
|
} elsif ($rr->type eq "CNAME") {
|
||||||
|
print STDERR 'c' if $opt_d;
|
||||||
|
($name, $aliases, $addrtype, $length,
|
||||||
|
@addrs)=gethostbyname($rr->cname);
|
||||||
|
if (&isipv4addr($rr->cname)) {
|
||||||
|
&printerr("BAD", $rr->name
|
||||||
|
." CNAME ". $rr->cname .": alias must be a hostname\n");
|
||||||
|
}
|
||||||
|
# if (!(($name, $aliases, $addrtype, $length,
|
||||||
|
# @addrs)=gethostbyname($rr->cname))) {
|
||||||
|
# &printerr("FAIL", "gethostbyname(". $rr->cname ."): $!\n");
|
||||||
|
# }
|
||||||
|
# else {
|
||||||
|
if (!$name) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." CNAME ". $rr->cname .": unknown host\n");
|
||||||
|
} elsif (!&equal($name,$rr->cname)) {
|
||||||
|
&printerr("WARN", $rr->name
|
||||||
|
." CNAME ". $rr->cname .": CNAME (to $name)\n");
|
||||||
|
}
|
||||||
|
# }
|
||||||
|
}
|
||||||
|
}
|
||||||
|
print STDERR "\n" if $opt_d;
|
||||||
|
close(FILE);
|
||||||
|
}
|
||||||
|
|
||||||
|
# prints an error message, suppressing duplicates
|
||||||
|
sub printerr {
|
||||||
|
my ($type, $err)=@_;
|
||||||
|
if ($errlist{$err}==undef) {
|
||||||
|
print "$type: $err";
|
||||||
|
$num_error{$type}++;
|
||||||
|
print STDERR "!" if $opt_d;
|
||||||
|
$errlist{$err}=1;
|
||||||
|
} else {
|
||||||
|
print STDERR "." if $opt_d;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
sub equal {
|
||||||
|
# Do case-insensitive string comparisons
|
||||||
|
local ($one)= $_[0];
|
||||||
|
local ($two)= $_[1];
|
||||||
|
$stripone=$one;
|
||||||
|
if (chop($stripone) eq '.') {
|
||||||
|
$one=$stripone;
|
||||||
|
}
|
||||||
|
$striptwo=$two;
|
||||||
|
if (chop($striptwo) eq '.') {
|
||||||
|
$two=$striptwo;
|
||||||
|
}
|
||||||
|
$one =~ tr/A-Z/a-z/;
|
||||||
|
$two =~ tr/A-Z/a-z/;
|
||||||
|
return ($one eq $two);
|
||||||
|
}
|
||||||
|
|
||||||
|
# check if argument looks like an IPv4 address
|
||||||
|
sub isipv4addr {
|
||||||
|
my ($host)=$_[0];
|
||||||
|
my ($one,$two,$three,$four);
|
||||||
|
($one,$two,$three,$four)=split(/\./,$host);
|
||||||
|
my $whole="$one$two$three$four";
|
||||||
|
# strings evaluated as numbers are zero
|
||||||
|
return (($whole+0) eq $whole);
|
||||||
|
}
|
||||||
|
sub matchaddrlist {
|
||||||
|
local($match)=pack('C4', reverse(split(/\./,$_[0],4)));
|
||||||
|
local($found)=0;
|
||||||
|
foreach $i (@addrs) {
|
||||||
|
$found=1 if ($i eq $match);
|
||||||
|
}
|
||||||
|
return $found;
|
||||||
|
}
|
||||||
|
|
||||||
|
# there's a better way to do this, it just hasn't evolved from
|
||||||
|
# my brain to this program yet.
|
||||||
|
sub byhostname {
|
||||||
|
@c = reverse(split(/\./,$a));
|
||||||
|
@d = reverse(split(/\./,$b));
|
||||||
|
for ($i=0;$i<=(($#c > $#d) ? $#c : $#d) ;$i++) {
|
||||||
|
next if $c[$i] eq $d[$i];
|
||||||
|
return -1 if $c[$i] eq "";
|
||||||
|
return 1 if $d[$i] eq "";
|
||||||
|
if ($c[$i] eq int($c[$i])) {
|
||||||
|
# numeric
|
||||||
|
return $c[$i] <=> $d[$i];
|
||||||
|
}
|
||||||
|
else {
|
||||||
|
# string
|
||||||
|
return $c[$i] cmp $d[$i];
|
||||||
|
}
|
||||||
|
}
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
sub checklamer {
|
||||||
|
my ($zone,$nameserver)=@_;
|
||||||
|
my ($packet) = new Net::DNS::Packet($zone, "SOA", "IN");
|
||||||
|
my ($soa_req);
|
||||||
|
my ($res) = new Net::DNS::Resolver;
|
||||||
|
unless ($res->nameservers($nameserver)) {
|
||||||
|
&printerr("FAIL", "Cannot find address for nameserver: ".
|
||||||
|
$res->errorstring. "\n");
|
||||||
|
}
|
||||||
|
$soa_req = $res->send($packet);
|
||||||
|
unless (defined($soa_req)) {
|
||||||
|
&printerr("FAIL",
|
||||||
|
"Cannot get SOA record for $zone from $nameserver (lame?): ".
|
||||||
|
$res->errorstring ."\n");
|
||||||
|
return;
|
||||||
|
}
|
||||||
|
&printerr("BAD", "$zone NS $nameserver: lame NS delegation\n")
|
||||||
|
unless ($soa_req->header->aa);
|
||||||
|
return;
|
||||||
|
}
|
||||||
221
dns/dnswalk/dnswalk.1
Normal file
221
dns/dnswalk/dnswalk.1
Normal file
|
|
@ -0,0 +1,221 @@
|
||||||
|
.TH DNSWALK 1
|
||||||
|
.SH NAME
|
||||||
|
dnswalk \- A DNS database debugger
|
||||||
|
.SH SYNOPSIS
|
||||||
|
.B dnswalk
|
||||||
|
[
|
||||||
|
.BR \- adilrfFm
|
||||||
|
]
|
||||||
|
.I domain.
|
||||||
|
.SH "DESCRIPTION"
|
||||||
|
.B dnswalk
|
||||||
|
is a DNS debugger. It performs zone transfers of specified domains,
|
||||||
|
and checks the database in numerous ways for internal consistency, as
|
||||||
|
well as for correctness according to accepted practices with the Domain
|
||||||
|
Name System.
|
||||||
|
.PP
|
||||||
|
The
|
||||||
|
.I domain
|
||||||
|
name specified on the command line MUST end with a '.'.
|
||||||
|
You can specify a forward domain, such as
|
||||||
|
.B dnswalk podunk.edu.
|
||||||
|
or a reverse domain, such as
|
||||||
|
.B dnswalk 3.2.1.in-addr.arpa.
|
||||||
|
.SH OPTIONS
|
||||||
|
.PD 0
|
||||||
|
.TP
|
||||||
|
.BI \-r
|
||||||
|
Recursively descend sub-domains of the specified
|
||||||
|
domain. Use with care.
|
||||||
|
.TP
|
||||||
|
.BI \-a
|
||||||
|
Turn on warning of duplicate A records. (see below)
|
||||||
|
.TP
|
||||||
|
.BI \-d
|
||||||
|
Print debugging and 'status' information to stderr.
|
||||||
|
(Use only if redirecting stdout) See DIAGNOSTICS section.
|
||||||
|
.TP
|
||||||
|
.BI \-m
|
||||||
|
Perform checks only if the zone has been modified since the previous run.
|
||||||
|
.TP
|
||||||
|
.BI \-F
|
||||||
|
perform "fascist" checking. When checking an A record,
|
||||||
|
compare the PTR name for each IP address with the forward
|
||||||
|
name and report mismatches. (see below) I recommend
|
||||||
|
you try this option at least once to see what sorts of
|
||||||
|
errors pop up - you might be surprised!.
|
||||||
|
.TP
|
||||||
|
.BI \-i
|
||||||
|
Suppress check for invalid characters in a domain name. (see below)
|
||||||
|
.TP
|
||||||
|
.BI \-l
|
||||||
|
Perform "lame delegation" checking. For every NS record,
|
||||||
|
check to see that the listed host is indeed returning
|
||||||
|
authoritative answers for this domain.
|
||||||
|
.TP
|
||||||
|
.SH ERRORS
|
||||||
|
The following the list of error messages that
|
||||||
|
.B dnswalk
|
||||||
|
will return
|
||||||
|
if it sees a potential problem with the database. Duplicate messages
|
||||||
|
will be suppressed automatically for each zone. Error messages are
|
||||||
|
prefixed by a keyword indiciating the message type: "WARN" (possible
|
||||||
|
data problem), "FAIL" (failure to access data), or "BAD" (invalid data).
|
||||||
|
.B dnswalk
|
||||||
|
exits with a return code equal to the number of "BAD" errors.
|
||||||
|
.TP
|
||||||
|
.PD 0
|
||||||
|
.BI "X PTR Y: unknown host"
|
||||||
|
X is a PTR record to Y, but Y is not a valid host (no A record).
|
||||||
|
These are often left over from when someone deleted a host from
|
||||||
|
the DNS and forgot to delete the PTR record.
|
||||||
|
.TP
|
||||||
|
.BI "X PTR Y: A record not found"
|
||||||
|
X is a PTR record to Y, but the IP address associated with the PTR
|
||||||
|
record is not listed as an address for Y. There should be an A
|
||||||
|
record for every valid IP address for a host. Many Internet services
|
||||||
|
will not talk to you if you have mismatched PTR records.
|
||||||
|
.TP
|
||||||
|
.BI "X PTR Y: CNAME (to Z)"
|
||||||
|
X is a PTR record to Y, but Y is a CNAME to Z. PTR records MUST point
|
||||||
|
to the canonical name of a host, not an alias.
|
||||||
|
.TP
|
||||||
|
.BI "X CNAME Y: unknown host"
|
||||||
|
X is aliased to Y, but Y is not a valid host (no A record).
|
||||||
|
.TP
|
||||||
|
.BI "X CNAME Y: CNAME (to Z)"
|
||||||
|
X is aliased to Y, but Y is aliased to Z. CNAMEs should not be chained.
|
||||||
|
.TP
|
||||||
|
.BI "X MX Y: unknown host"
|
||||||
|
X is an MX to Y, but Y is not a valid host (no A record).
|
||||||
|
.TP
|
||||||
|
.BI "X MX Y: CNAME (to Z)"
|
||||||
|
X is an MX to Y, but Y is an alias for Z. MX records must point to
|
||||||
|
the canonical name, not an alias.
|
||||||
|
.TP
|
||||||
|
.BI "X A Y: no PTR record"
|
||||||
|
X has an IP address Y, but there is no PTR record to map the IP address
|
||||||
|
Y back to a hostname (usually X). Many Internet servers (such as anonymous
|
||||||
|
FTP servers) will not talk to addresses that don't have PTR records.
|
||||||
|
.TP
|
||||||
|
.BI "warning: X has only one authoritative nameserver"
|
||||||
|
Zones must have at least one authoritative nameserver, in case
|
||||||
|
one is down or unreachable. Make sure the parent and child domains
|
||||||
|
list all authoritative nameservers for a zone.
|
||||||
|
.TP
|
||||||
|
.BI "Cannot check X: no available nameservers!"
|
||||||
|
The X zone was delegated with NS records but all the nameservers
|
||||||
|
for the zone are either unavailable or say that they have no data for
|
||||||
|
the zone (are lame). Verify that the X zone isn't a typo, and if so
|
||||||
|
make sure that all the listed nameservers are configured to answer
|
||||||
|
with data for the zone.
|
||||||
|
.TP
|
||||||
|
.BI "X: invalid character(s) in name"
|
||||||
|
Allowable characters in a domain name are the ASCII letters a through Z
|
||||||
|
the digits 0 through 9,
|
||||||
|
and the "-" character. A "." may be used only as a domain separator.
|
||||||
|
(checking can be suppressed with
|
||||||
|
.B \-i
|
||||||
|
)
|
||||||
|
.TP
|
||||||
|
.BI "X: domain occurred twice, forgot trailing '.'?"
|
||||||
|
A sanity check which looks for "dom.ain.dom.ain." in a name. This
|
||||||
|
is often caused by forgetting to put a trailing '.' on the end of
|
||||||
|
a name.
|
||||||
|
.TP
|
||||||
|
(with -a switch)
|
||||||
|
.TP
|
||||||
|
.BI "X: possible duplicate A record (glue of Z?)"
|
||||||
|
A duplicate A records is listed for X. NOTE: this is most
|
||||||
|
often caused by the practice of always putting A records for all
|
||||||
|
secondaries after NS glue records. While this is not an error, it is
|
||||||
|
usually redundant and makes changing IP addresses later more difficult,
|
||||||
|
since they occur more than one time in the file (and in multiple
|
||||||
|
files). You may get spurious errors, mostly because of a quirk in
|
||||||
|
BIND releases before 4.9.x that reports cached glue A records in a zone
|
||||||
|
transfer even though they don't exist in the original zone file.
|
||||||
|
.TP
|
||||||
|
(with -F switch)
|
||||||
|
.TP
|
||||||
|
.BI "X A Y: points to Z"
|
||||||
|
X has Y for an IP address, but the PTR record associated with Y
|
||||||
|
returns "Z" as the name associated with that host. This is not
|
||||||
|
necessarily an error (for example if you have an A record for your
|
||||||
|
domain name), but can be useful to check for A records which point
|
||||||
|
to the wrong host, or PTR records that point to the wrong host.
|
||||||
|
.TP
|
||||||
|
.BI "Cannot find address for nameserver X"
|
||||||
|
This error is generated if the address for a delegated nameserver X
|
||||||
|
cannot be resolved. This could be a lame delegation (due to a typo
|
||||||
|
in delegation), or a temporary DNS error.
|
||||||
|
.TP
|
||||||
|
(with -l switch)
|
||||||
|
.TP
|
||||||
|
.BI "X NS Y: lame NS delegation"
|
||||||
|
Y is a listed nameserver for zone X, but Y is not returning
|
||||||
|
authoritative data for zone X. This is usually the result of a
|
||||||
|
lack of communication on the part of the respective hostmasters. Lame
|
||||||
|
delegations are not fatal problems except in severe cases, they just
|
||||||
|
tend to create significant increases in DNS traffic. NS records for
|
||||||
|
the parent and child domains should be consistent, and each server
|
||||||
|
listed in the NS record MUST be able to answer with authoritative data,
|
||||||
|
either by being a primary or secondary for the zone.
|
||||||
|
.TP
|
||||||
|
.BI "Cannot get SOA record for X from Y (lame?)"
|
||||||
|
This error is generated if dnswalk cannot get the SOA record for
|
||||||
|
zone X from the nameserver Y. This could
|
||||||
|
mean a lame delegation, or simply that the host is temporarily
|
||||||
|
unreachable.
|
||||||
|
.SH "SEE ALSO"
|
||||||
|
.nf
|
||||||
|
RFC 1034 - "DOMAIN NAMES - CONCEPTS AND FACILITIES"
|
||||||
|
RFC 1035 - "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION"
|
||||||
|
RFC 1123 - "Requirements for Internet Hosts -- Application and Support"
|
||||||
|
Paul Albitz, Cricket Liu: "DNS and BIND" O'Reilly & Associates.
|
||||||
|
.SH DIAGNOSTICS
|
||||||
|
When invoked with the
|
||||||
|
.B \-d
|
||||||
|
option,
|
||||||
|
.B dnswalk
|
||||||
|
will print status information to stderr. It consists of information
|
||||||
|
about what zone is being checked, and a single letter corresponding
|
||||||
|
to the resource record checked, and any errors.
|
||||||
|
.TP
|
||||||
|
.BI a
|
||||||
|
A record
|
||||||
|
.TP
|
||||||
|
.BI c
|
||||||
|
CNAME record
|
||||||
|
.TP
|
||||||
|
.BI p
|
||||||
|
PTR record
|
||||||
|
.TP
|
||||||
|
.BI m
|
||||||
|
MX record
|
||||||
|
.TP
|
||||||
|
.BI s
|
||||||
|
SOA record
|
||||||
|
.TP
|
||||||
|
.BI !
|
||||||
|
An error occurred
|
||||||
|
.TP
|
||||||
|
.BI .
|
||||||
|
A previous error in the zone was repeated, but suppressed.
|
||||||
|
.PP
|
||||||
|
.SH BUGS
|
||||||
|
dnswalk will make the directory tree before it has a chance to
|
||||||
|
find out that you gave it a bogus domain name.
|
||||||
|
.PP
|
||||||
|
When checking lots of hosts and lots of options, it is very
|
||||||
|
slow. Running dnswalk on a machine with a local nameserver helps
|
||||||
|
considerably.
|
||||||
|
.PP
|
||||||
|
Perl's gethostby{name,addr}() routine doesn't seem to
|
||||||
|
consistently return an error whenever it is unable to resolve an
|
||||||
|
address. Argh. This will mean lots of "no PTR record" and "host unknown"
|
||||||
|
errors if a server is unavailable, or for some reason the lookup fails.
|
||||||
|
You may get strange error messages if your perl was compiled without
|
||||||
|
support for herror().
|
||||||
|
.PP
|
||||||
|
.SH AUTHOR
|
||||||
|
David Barr <barr@cis.ohio-state.edu>
|
||||||
96
dns/dnswalk/dnswalk.errors
Normal file
96
dns/dnswalk/dnswalk.errors
Normal file
|
|
@ -0,0 +1,96 @@
|
||||||
|
The following the list of error messages that dnswalk will
|
||||||
|
return if it sees a potential problem with the database.
|
||||||
|
Duplicate messages will be suppressed automatically for each
|
||||||
|
zone.
|
||||||
|
X PTR Y: unknown host
|
||||||
|
X is a PTR record to Y, but Y is not a valid host (no A
|
||||||
|
record). These are often left over from when someone
|
||||||
|
deleted a host from the DNS and forgot to delete the
|
||||||
|
PTR record. These records should be removed.
|
||||||
|
X PTR Y: A record not found
|
||||||
|
X is a PTR record to Y, but the IP address associated
|
||||||
|
with the PTR record is not listed as an address for Y.
|
||||||
|
There should be an A record for every valid IP address
|
||||||
|
for a host. Many Internet services will not talk to
|
||||||
|
you if you have mismatched PTR records.
|
||||||
|
X PTR Y: CNAME (to Z)
|
||||||
|
X is a PTR record to Y, but Y is a CNAME to Z. PTR
|
||||||
|
records should point to the real name of a host, not an
|
||||||
|
alias.
|
||||||
|
X CNAME Y: unknown host
|
||||||
|
X is aliased to Y, but Y is not a valid host (no A
|
||||||
|
record). This is a stale entry and should be removed.
|
||||||
|
X CNAME Y: CNAME (to Z)
|
||||||
|
X is aliased to Y, but Y is aliased to Z. CNAMEs
|
||||||
|
should not be chained together. It has been known to
|
||||||
|
cause problems with some software.
|
||||||
|
X MX Y: unknown host
|
||||||
|
X is an MX to Y, but Y is not a valid host (no A
|
||||||
|
record). This is a stale entry and should be removed.
|
||||||
|
X MX Y: CNAME (to Z)
|
||||||
|
X is an MX to Y, but Y is an alias for Z. MX records
|
||||||
|
must point to the canonical name, not an alias.
|
||||||
|
X A Y: no PTR record
|
||||||
|
X has an IP address Y, but there is no PTR record to
|
||||||
|
map the IP address Y back to a hostname (usually X).
|
||||||
|
Many Internet servers (such as anonymous FTP servers)
|
||||||
|
will not talk to addresses that don't have PTR records.
|
||||||
|
warning: X has only one authoritative nameserver
|
||||||
|
Zones should have more than one authoritative name-
|
||||||
|
server, in case one is down or unreachable. Preferably
|
||||||
|
one should be off-site. Make sure the parent and child
|
||||||
|
nameservers list all authoritative nameservers for a
|
||||||
|
zone in the NS list.
|
||||||
|
X: invalid character(s) in name
|
||||||
|
Allowable characters in a domain name are the ASCII
|
||||||
|
letters a through Z the digits 0 through 9, and the "-"
|
||||||
|
character. A "." may be used only as a domain separa-
|
||||||
|
tor. Using non-standard characters can cause unexpected
|
||||||
|
software problems.
|
||||||
|
X: domain occurred twice, forgot trailing '.'?
|
||||||
|
A sanity check which looks for "dom.ain.dom.ain." in a
|
||||||
|
name. This is often caused by forgetting to put a
|
||||||
|
trailing '.' on the end of a name.
|
||||||
|
X A Y: points to Z
|
||||||
|
X has Y for an IP address, but the PTR record associ-
|
||||||
|
ated with Y returns "Z" as the name associated with
|
||||||
|
that host. This is not necessarily an error (for exam-
|
||||||
|
ple if you have an A record for your domain name), but
|
||||||
|
may be an indication of an A record which points to the
|
||||||
|
wrong host, or a PTR record that points to the wrong
|
||||||
|
host. You will get this error if you are trying to
|
||||||
|
alias one host to another with an A record. You should
|
||||||
|
use a CNAME instead.
|
||||||
|
X NS Y: lame NS delegation
|
||||||
|
Y is a listed nameserver for zone X, but Y is not
|
||||||
|
returning authoritative data for zone X. This is usu-
|
||||||
|
ally the result of a lack of communication on the part
|
||||||
|
of the respective hostmasters. Lame delegations are
|
||||||
|
not fatal problems except in severe cases, they just
|
||||||
|
tend to create significant increases in DNS traffic.
|
||||||
|
NS records for the parent and child domains should be
|
||||||
|
consistent, and each server listed in the NS record
|
||||||
|
MUST be able to answer with authoritative data, by
|
||||||
|
being explicitly configured as a primary or secondary
|
||||||
|
for the zone.
|
||||||
|
X NS Y: nameserver error (lame?)
|
||||||
|
These are any errors returned while contacting other
|
||||||
|
nameservers (like connection refused or timeout) This
|
||||||
|
could mean a lame delegation (the host is not running
|
||||||
|
a nameserver or is misconfigured), or simply that the
|
||||||
|
nameserver is temporarily unreachable.
|
||||||
|
Cannot check X: no available nameservers!
|
||||||
|
The X zone was delegated with NS records but all the
|
||||||
|
nameservers for the zone are either unavailable or say
|
||||||
|
that they have no data for the zone (are lame). Verify
|
||||||
|
that the X zone isn't a typo, and if not make sure that
|
||||||
|
all the listed nameservers are configured to answer
|
||||||
|
with data for the zone.
|
||||||
|
|
||||||
|
SEE ALSO
|
||||||
|
RFC 1034 - "DOMAIN NAMES - CONCEPTS AND FACILITIES"
|
||||||
|
RFC 1035 - "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION"
|
||||||
|
RFC 1123 - "Requirements for Internet Hosts -- Application and Support"
|
||||||
|
Paul Albitz, Cricket Liu: "DNS and BIND" O'Reilly & Associates.
|
||||||
|
RFC 1912 - "Common DNS Operational and Configuration Errors"
|
||||||
|
http://www.dns.net/dnsrd/ - DNS Resources Directory
|
||||||
16
dns/dnswalk/do-dnswalk
Executable file
16
dns/dnswalk/do-dnswalk
Executable file
|
|
@ -0,0 +1,16 @@
|
||||||
|
#!/bin/sh
|
||||||
|
# Here's an example script for a hostmaster of a large site
|
||||||
|
# to automate the process
|
||||||
|
# You can also run "./makereports <logfile" to generate an error report for
|
||||||
|
# each hostmaster. Then cd to the rep.orts directory, remove any files
|
||||||
|
# you don't wish to send, then run "../sendreports"
|
||||||
|
# try adding '-F' here once just to see what pops up
|
||||||
|
flags='-r -d'
|
||||||
|
logfile=podunk.errors
|
||||||
|
trap "" 2 15;
|
||||||
|
exec > ${logfile}
|
||||||
|
./dnswalk ${flags} $* podunk.edu.
|
||||||
|
./dnswalk ${flags} $* 1.1.in-addr.arpa.
|
||||||
|
./dnswalk ${flags} $* 2.1.in-addr.arpa.
|
||||||
|
./dnswalk ${flags} $* 1.2.1.in-addr.arpa.
|
||||||
|
./dnswalk ${flags} $* 2.2.1.in-addr.arpa.
|
||||||
30
dns/dnswalk/makereports
Executable file
30
dns/dnswalk/makereports
Executable file
|
|
@ -0,0 +1,30 @@
|
||||||
|
#!/usr/contrib/bin/perl
|
||||||
|
# This takes output from dnswalk and makes a "rep.orts" directory
|
||||||
|
# with one file per contact. Great for sending mail to all the admins.
|
||||||
|
|
||||||
|
mkdir("rep.orts",0777);
|
||||||
|
|
||||||
|
while (<>) {
|
||||||
|
if (/^Checking (.*).$/) {
|
||||||
|
$zone=$1;
|
||||||
|
next;
|
||||||
|
}
|
||||||
|
if (/^warning: .* has /) { # ugly
|
||||||
|
$warning=$_;
|
||||||
|
next;
|
||||||
|
}
|
||||||
|
if (/^SOA.*contact=(.*)$/) {
|
||||||
|
close(REPORT);
|
||||||
|
$contact=$1;
|
||||||
|
$contact=~ tr/A-Z/a-z/;
|
||||||
|
print "writing report for $contact\n";
|
||||||
|
open(REPORT,">>rep.orts/$contact") || die "cannot write to rep.orts/$1: $!\n";
|
||||||
|
print REPORT "Potential errors for zone: $zone\n";
|
||||||
|
if ($warning) {
|
||||||
|
print REPORT $warning;
|
||||||
|
undef $warning;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
print REPORT;
|
||||||
|
}
|
||||||
|
close(REPORT);
|
||||||
899
dns/dnswalk/rfc1912.txt
Normal file
899
dns/dnswalk/rfc1912.txt
Normal file
|
|
@ -0,0 +1,899 @@
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Network Working Group D. Barr
|
||||||
|
Request for Comments: 1912 The Pennsylvania State University
|
||||||
|
Obsoletes: 1537 February 1996
|
||||||
|
Category: Informational
|
||||||
|
|
||||||
|
|
||||||
|
Common DNS Operational and Configuration Errors
|
||||||
|
|
||||||
|
Status of this Memo
|
||||||
|
|
||||||
|
This memo provides information for the Internet community. This memo
|
||||||
|
does not specify an Internet standard of any kind. Distribution of
|
||||||
|
this memo is unlimited.
|
||||||
|
|
||||||
|
Abstract
|
||||||
|
|
||||||
|
This memo describes errors often found in both the operation of
|
||||||
|
Domain Name System (DNS) servers, and in the data that these DNS
|
||||||
|
servers contain. This memo tries to summarize current Internet
|
||||||
|
requirements as well as common practice in the operation and
|
||||||
|
configuration of the DNS. This memo also tries to summarize or
|
||||||
|
expand upon issues raised in [RFC 1537].
|
||||||
|
|
||||||
|
1. Introduction
|
||||||
|
|
||||||
|
Running a nameserver is not a trivial task. There are many things
|
||||||
|
that can go wrong, and many decisions have to be made about what data
|
||||||
|
to put in the DNS and how to set up servers. This memo attempts to
|
||||||
|
address many of the common mistakes and pitfalls that are made in DNS
|
||||||
|
data as well as in the operation of nameservers. Discussions are
|
||||||
|
also made regarding some other relevant issues such as server or
|
||||||
|
resolver bugs, and a few political issues with respect to the
|
||||||
|
operation of DNS on the Internet.
|
||||||
|
|
||||||
|
2. DNS Data
|
||||||
|
|
||||||
|
This section discusses problems people typically have with the DNS
|
||||||
|
data in their nameserver, as found in the zone data files that the
|
||||||
|
nameserver loads into memory.
|
||||||
|
|
||||||
|
2.1 Inconsistent, Missing, or Bad Data
|
||||||
|
|
||||||
|
Every Internet-reachable host should have a name. The consequences
|
||||||
|
of this are becoming more and more obvious. Many services available
|
||||||
|
on the Internet will not talk to you if you aren't correctly
|
||||||
|
registered in the DNS.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 1]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
Make sure your PTR and A records match. For every IP address, there
|
||||||
|
should be a matching PTR record in the in-addr.arpa domain. If a
|
||||||
|
host is multi-homed, (more than one IP address) make sure that all IP
|
||||||
|
addresses have a corresponding PTR record (not just the first one).
|
||||||
|
Failure to have matching PTR and A records can cause loss of Internet
|
||||||
|
services similar to not being registered in the DNS at all. Also,
|
||||||
|
PTR records must point back to a valid A record, not a alias defined
|
||||||
|
by a CNAME. It is highly recommended that you use some software
|
||||||
|
which automates this checking, or generate your DNS data from a
|
||||||
|
database which automatically creates consistent data.
|
||||||
|
|
||||||
|
DNS domain names consist of "labels" separated by single dots. The
|
||||||
|
DNS is very liberal in its rules for the allowable characters in a
|
||||||
|
domain name. However, if a domain name is used to name a host, it
|
||||||
|
should follow rules restricting host names. Further if a name is
|
||||||
|
used for mail, it must follow the naming rules for names in mail
|
||||||
|
addresses.
|
||||||
|
|
||||||
|
Allowable characters in a label for a host name are only ASCII
|
||||||
|
letters, digits, and the `-' character. Labels may not be all
|
||||||
|
numbers, but may have a leading digit (e.g., 3com.com). Labels must
|
||||||
|
end and begin only with a letter or digit. See [RFC 1035] and [RFC
|
||||||
|
1123]. (Labels were initially restricted in [RFC 1035] to start with
|
||||||
|
a letter, and some older hosts still reportedly have problems with
|
||||||
|
the relaxation in [RFC 1123].) Note there are some Internet
|
||||||
|
hostnames which violate this rule (411.org, 1776.com). The presence
|
||||||
|
of underscores in a label is allowed in [RFC 1033], except [RFC 1033]
|
||||||
|
is informational only and was not defining a standard. There is at
|
||||||
|
least one popular TCP/IP implementation which currently refuses to
|
||||||
|
talk to hosts named with underscores in them. It must be noted that
|
||||||
|
the language in [1035] is such that these rules are voluntary -- they
|
||||||
|
are there for those who wish to minimize problems. Note that the
|
||||||
|
rules for Internet host names also apply to hosts and addresses used
|
||||||
|
in SMTP (See RFC 821).
|
||||||
|
|
||||||
|
If a domain name is to be used for mail (not involving SMTP), it must
|
||||||
|
follow the rules for mail in [RFC 822], which is actually more
|
||||||
|
liberal than the above rules. Labels for mail can be any ASCII
|
||||||
|
character except "specials", control characters, and whitespace
|
||||||
|
characters. "Specials" are specific symbols used in the parsing of
|
||||||
|
addresses. They are the characters "()<>@,;:\".[]". (The "!"
|
||||||
|
character wasn't in [RFC 822], however it also shouldn't be used due
|
||||||
|
to the conflict with UUCP mail as defined in RFC 976) However, since
|
||||||
|
today almost all names which are used for mail on the Internet are
|
||||||
|
also names used for hostnames, one rarely sees addresses using these
|
||||||
|
relaxed standard, but mail software should be made liberal and robust
|
||||||
|
enough to accept them.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 2]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
You should also be careful to not have addresses which are valid
|
||||||
|
alternate syntaxes to the inet_ntoa() library call. For example 0xe
|
||||||
|
is a valid name, but if you were to type "telnet 0xe", it would try
|
||||||
|
to connect to IP address 0.0.0.14. It is also rumored that there
|
||||||
|
exists some broken inet_ntoa() routines that treat an address like
|
||||||
|
x400 as an IP address.
|
||||||
|
|
||||||
|
Certain operating systems have limitations on the length of their own
|
||||||
|
hostname. While not strictly of issue to the DNS, you should be
|
||||||
|
aware of your operating system's length limits before choosing the
|
||||||
|
name of a host.
|
||||||
|
|
||||||
|
Remember that many resource records (abbreviated RR) take on more
|
||||||
|
than one argument. HINFO requires two arguments, as does RP. If you
|
||||||
|
don't supply enough arguments, servers sometime return garbage for
|
||||||
|
the missing fields. If you need to include whitespace within any
|
||||||
|
data, you must put the string in quotes.
|
||||||
|
|
||||||
|
2.2 SOA records
|
||||||
|
|
||||||
|
In the SOA record of every zone, remember to fill in the e-mail
|
||||||
|
address that will get to the person who maintains the DNS at your
|
||||||
|
site (commonly referred to as "hostmaster"). The `@' in the e-mail
|
||||||
|
must be replaced by a `.' first. Do not try to put an `@' sign in
|
||||||
|
this address. If the local part of the address already contains a
|
||||||
|
`.' (e.g., John.Smith@widget.xx), then you need to quote the `.' by
|
||||||
|
preceding it with `\' character. (e.g., to become
|
||||||
|
John\.Smith.widget.xx) Alternately (and preferred), you can just use
|
||||||
|
the generic name `hostmaster', and use a mail alias to redirect it to
|
||||||
|
the appropriate persons. There exists software which uses this field
|
||||||
|
to automatically generate the e-mail address for the zone contact.
|
||||||
|
This software will break if this field is improperly formatted. It
|
||||||
|
is imperative that this address get to one or more real persons,
|
||||||
|
because it is often used for everything from reporting bad DNS data
|
||||||
|
to reporting security incidents.
|
||||||
|
|
||||||
|
Even though some BIND versions allow you to use a decimal in a serial
|
||||||
|
number, don't. A decimal serial number is converted to an unsigned
|
||||||
|
32-bit integer internally anyway. The formula for a n.m serial
|
||||||
|
number is n*10^(3+int(0.9+log10(m))) + m which translates to
|
||||||
|
something rather unexpected. For example it's routinely possible
|
||||||
|
with a decimal serial number (perhaps automatically generated by
|
||||||
|
SCCS) to be incremented such that it is numerically larger, but after
|
||||||
|
the above conversion yield a serial number which is LOWER than
|
||||||
|
before. Decimal serial numbers have been officially deprecated in
|
||||||
|
recent BIND versions. The recommended syntax is YYYYMMDDnn
|
||||||
|
(YYYY=year, MM=month, DD=day, nn=revision number. This won't
|
||||||
|
overflow until the year 4294.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 3]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
Choose logical values for the timer values in the SOA record (note
|
||||||
|
values below must be expressed as seconds in the zone data):
|
||||||
|
|
||||||
|
Refresh: How often a secondary will poll the primary server to see
|
||||||
|
if the serial number for the zone has increased (so it knows
|
||||||
|
to request a new copy of the data for the zone). Set this to
|
||||||
|
how long your secondaries can comfortably contain out-of-date
|
||||||
|
data. You can keep it short (20 mins to 2 hours) if you
|
||||||
|
aren't worried about a small increase in bandwidth used, or
|
||||||
|
longer (2-12 hours) if your Internet connection is slow or is
|
||||||
|
started on demand. Recent BIND versions (4.9.3) have optional
|
||||||
|
code to automatically notify secondaries that data has
|
||||||
|
changed, allowing you to set this TTL to a long value (one
|
||||||
|
day, or more).
|
||||||
|
|
||||||
|
Retry: If a secondary was unable to contact the primary at the
|
||||||
|
last refresh, wait the retry value before trying again. This
|
||||||
|
value isn't as important as others, unless the secondary is on
|
||||||
|
a distant network from the primary or the primary is more
|
||||||
|
prone to outages. It's typically some fraction of the refresh
|
||||||
|
interval.
|
||||||
|
|
||||||
|
|
||||||
|
Expire: How long a secondary will still treat its copy of the zone
|
||||||
|
data as valid if it can't contact the primary. This value
|
||||||
|
should be greater than how long a major outage would typically
|
||||||
|
last, and must be greater than the minimum and retry
|
||||||
|
intervals, to avoid having a secondary expire the data before
|
||||||
|
it gets a chance to get a new copy. After a zone is expired a
|
||||||
|
secondary will still continue to try to contact the primary,
|
||||||
|
but it will no longer provide nameservice for the zone. 2-4
|
||||||
|
weeks are suggested values.
|
||||||
|
|
||||||
|
Minimum: The default TTL (time-to-live) for resource records --
|
||||||
|
how long data will remain in other nameservers' cache. ([RFC
|
||||||
|
1035] defines this to be the minimum value, but servers seem
|
||||||
|
to always implement this as the default value) This is by far
|
||||||
|
the most important timer. Set this as large as is comfortable
|
||||||
|
given how often you update your nameserver. If you plan to
|
||||||
|
make major changes, it's a good idea to turn this value down
|
||||||
|
temporarily beforehand. Then wait the previous minimum value,
|
||||||
|
make your changes, verify their correctness, and turn this
|
||||||
|
value back up. 1-5 days are typical values. Remember this
|
||||||
|
value can be overridden on individual resource records.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 4]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
As you can see, the typical values above for the timers vary widely.
|
||||||
|
Popular documentation like [RFC 1033] recommended a day for the
|
||||||
|
minimum TTL, which is now considered too low except for zones with
|
||||||
|
data that vary regularly. Once a DNS stabilizes, values on the order
|
||||||
|
of 3 or more days are recommended. It is also recommended that you
|
||||||
|
individually override the TTL on certain RRs which are often
|
||||||
|
referenced and don't often change to have very large values (1-2
|
||||||
|
weeks). Good examples of this are the MX, A, and PTR records of your
|
||||||
|
mail host(s), the NS records of your zone, and the A records of your
|
||||||
|
nameservers.
|
||||||
|
|
||||||
|
2.3 Glue A Records
|
||||||
|
|
||||||
|
Glue records are A records that are associated with NS records to
|
||||||
|
provide "bootstrapping" information to the nameserver. For example:
|
||||||
|
|
||||||
|
podunk.xx. in ns ns1.podunk.xx.
|
||||||
|
in ns ns2.podunk.xx.
|
||||||
|
ns1.podunk.xx. in a 1.2.3.4
|
||||||
|
ns2.podunk.xx. in a 1.2.3.5
|
||||||
|
|
||||||
|
Here, the A records are referred to as "Glue records".
|
||||||
|
|
||||||
|
Glue records are required only in forward zone files for nameservers
|
||||||
|
that are located in the subdomain of the current zone that is being
|
||||||
|
delegated. You shouldn't have any A records in an in-addr.arpa zone
|
||||||
|
file (unless you're using RFC 1101-style encoding of subnet masks).
|
||||||
|
|
||||||
|
If your nameserver is multi-homed (has more than one IP address), you
|
||||||
|
must list all of its addresses in the glue to avoid cache
|
||||||
|
inconsistency due to differing TTL values, causing some lookups to
|
||||||
|
not find all addresses for your nameserver.
|
||||||
|
|
||||||
|
Some people get in the bad habit of putting in a glue record whenever
|
||||||
|
they add an NS record "just to make sure". Having duplicate glue
|
||||||
|
records in your zone files just makes it harder when a nameserver
|
||||||
|
moves to a new IP address, or is removed. You'll spend hours trying
|
||||||
|
to figure out why random people still see the old IP address for some
|
||||||
|
host, because someone forgot to change or remove a glue record in
|
||||||
|
some other file. Newer BIND versions will ignore these extra glue
|
||||||
|
records in local zone files.
|
||||||
|
|
||||||
|
Older BIND versions (4.8.3 and previous) have a problem where it
|
||||||
|
inserts these extra glue records in the zone transfer data to
|
||||||
|
secondaries. If one of these glues is wrong, the error can be
|
||||||
|
propagated to other nameservers. If two nameservers are secondaries
|
||||||
|
for other zones of each other, it's possible for one to continually
|
||||||
|
pass old glue records back to the other. The only way to get rid of
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 5]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
the old data is to kill both of them, remove the saved backup files,
|
||||||
|
and restart them. Combined with that those same versions also tend
|
||||||
|
to become infected more easily with bogus data found in other non-
|
||||||
|
secondary nameservers (like the root zone data).
|
||||||
|
|
||||||
|
2.4 CNAME records
|
||||||
|
|
||||||
|
A CNAME record is not allowed to coexist with any other data. In
|
||||||
|
other words, if suzy.podunk.xx is an alias for sue.podunk.xx, you
|
||||||
|
can't also have an MX record for suzy.podunk.edu, or an A record, or
|
||||||
|
even a TXT record. Especially do not try to combine CNAMEs and NS
|
||||||
|
records like this!:
|
||||||
|
|
||||||
|
|
||||||
|
podunk.xx. IN NS ns1
|
||||||
|
IN NS ns2
|
||||||
|
IN CNAME mary
|
||||||
|
mary IN A 1.2.3.4
|
||||||
|
|
||||||
|
|
||||||
|
This is often attempted by inexperienced administrators as an obvious
|
||||||
|
way to allow your domain name to also be a host. However, DNS
|
||||||
|
servers like BIND will see the CNAME and refuse to add any other
|
||||||
|
resources for that name. Since no other records are allowed to
|
||||||
|
coexist with a CNAME, the NS entries are ignored. Therefore all the
|
||||||
|
hosts in the podunk.xx domain are ignored as well!
|
||||||
|
|
||||||
|
If you want to have your domain also be a host, do the following:
|
||||||
|
|
||||||
|
podunk.xx. IN NS ns1
|
||||||
|
IN NS ns2
|
||||||
|
IN A 1.2.3.4
|
||||||
|
mary IN A 1.2.3.4
|
||||||
|
|
||||||
|
Don't go overboard with CNAMEs. Use them when renaming hosts, but
|
||||||
|
plan to get rid of them (and inform your users). However CNAMEs are
|
||||||
|
useful (and encouraged) for generalized names for servers -- `ftp'
|
||||||
|
for your ftp server, `www' for your Web server, `gopher' for your
|
||||||
|
Gopher server, `news' for your Usenet news server, etc.
|
||||||
|
|
||||||
|
Don't forget to delete the CNAMEs associated with a host if you
|
||||||
|
delete the host it is an alias for. Such "stale CNAMEs" are a waste
|
||||||
|
of resources.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 6]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
Don't use CNAMEs in combination with RRs which point to other names
|
||||||
|
like MX, CNAME, PTR and NS. (PTR is an exception if you want to
|
||||||
|
implement classless in-addr delegation.) For example, this is
|
||||||
|
strongly discouraged:
|
||||||
|
|
||||||
|
podunk.xx. IN MX mailhost
|
||||||
|
mailhost IN CNAME mary
|
||||||
|
mary IN A 1.2.3.4
|
||||||
|
|
||||||
|
|
||||||
|
[RFC 1034] in section 3.6.2 says this should not be done, and [RFC
|
||||||
|
974] explicitly states that MX records shall not point to an alias
|
||||||
|
defined by a CNAME. This results in unnecessary indirection in
|
||||||
|
accessing the data, and DNS resolvers and servers need to work more
|
||||||
|
to get the answer. If you really want to do this, you can accomplish
|
||||||
|
the same thing by using a preprocessor such as m4 on your host files.
|
||||||
|
|
||||||
|
Also, having chained records such as CNAMEs pointing to CNAMEs may
|
||||||
|
make administration issues easier, but is known to tickle bugs in
|
||||||
|
some resolvers that fail to check loops correctly. As a result some
|
||||||
|
hosts may not be able to resolve such names.
|
||||||
|
|
||||||
|
Having NS records pointing to a CNAME is bad and may conflict badly
|
||||||
|
with current BIND servers. In fact, current BIND implementations
|
||||||
|
will ignore such records, possibly leading to a lame delegation.
|
||||||
|
There is a certain amount of security checking done in BIND to
|
||||||
|
prevent spoofing DNS NS records. Also, older BIND servers reportedly
|
||||||
|
will get caught in an infinite query loop trying to figure out the
|
||||||
|
address for the aliased nameserver, causing a continuous stream of
|
||||||
|
DNS requests to be sent.
|
||||||
|
|
||||||
|
2.5 MX records
|
||||||
|
|
||||||
|
It is a good idea to give every host an MX record, even if it points
|
||||||
|
to itself! Some mailers will cache MX records, but will always need
|
||||||
|
to check for an MX before sending mail. If a site does not have an
|
||||||
|
MX, then every piece of mail may result in one more resolver query,
|
||||||
|
since the answer to the MX query often also contains the IP addresses
|
||||||
|
of the MX hosts. Internet SMTP mailers are required by [RFC 1123] to
|
||||||
|
support the MX mechanism.
|
||||||
|
|
||||||
|
Put MX records even on hosts that aren't intended to send or receive
|
||||||
|
e-mail. If there is a security problem involving one of these hosts,
|
||||||
|
some people will mistakenly send mail to postmaster or root at the
|
||||||
|
site without checking first to see if it is a "real" host or just a
|
||||||
|
terminal or personal computer that's not set up to accept e-mail. If
|
||||||
|
you give it an MX record, then the e-mail can be redirected to a real
|
||||||
|
person. Otherwise mail can just sit in a queue for hours or days
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 7]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
until the mailer gives up trying to send it.
|
||||||
|
|
||||||
|
Don't forget that whenever you add an MX record, you need to inform
|
||||||
|
the target mailer if it is to treat the first host as "local". (The
|
||||||
|
"Cw" flag in sendmail, for example)
|
||||||
|
|
||||||
|
If you add an MX record which points to an external host (e.g., for
|
||||||
|
the purposes of backup mail routing) be sure to ask permission from
|
||||||
|
that site first. Otherwise that site could get rather upset and take
|
||||||
|
action (like throw your mail away, or appeal to higher authorities
|
||||||
|
like your parent DNS administrator or network provider.)
|
||||||
|
|
||||||
|
2.6 Other Resource Records
|
||||||
|
|
||||||
|
2.6.1 WKS
|
||||||
|
|
||||||
|
WKS records are deprecated in [RFC 1123]. They serve no known useful
|
||||||
|
function, except internally among LISP machines. Don't use them.
|
||||||
|
|
||||||
|
2.6.2 HINFO
|
||||||
|
|
||||||
|
On the issue HINFO records, some will argue that these is a security
|
||||||
|
problem (by broadcasting what vendor hardware and operating system
|
||||||
|
you so people can run systematic attacks on known vendor security
|
||||||
|
holes). If you do use them, you should keep up to date with known
|
||||||
|
vendor security problems. However, they serve a useful purpose.
|
||||||
|
Don't forget that HINFO requires two arguments, the hardware type,
|
||||||
|
and the operating system.
|
||||||
|
|
||||||
|
HINFO is sometimes abused to provide other information. The record
|
||||||
|
is meant to provide specific information about the machine itself.
|
||||||
|
If you need to express other information about the host in the DNS,
|
||||||
|
use TXT.
|
||||||
|
|
||||||
|
2.6.3 TXT
|
||||||
|
|
||||||
|
TXT records have no specific definition. You can put most anything
|
||||||
|
in them. Some use it for a generic description of the host, some put
|
||||||
|
specific information like its location, primary user, or maybe even a
|
||||||
|
phone number.
|
||||||
|
|
||||||
|
2.6.4 RP
|
||||||
|
|
||||||
|
RP records are relatively new. They are used to specify an e-mail
|
||||||
|
address (see first paragraph of section 2.2) of the "Responsible
|
||||||
|
Person" of the host, and the name of a TXT record where you can get
|
||||||
|
more information. See [RFC 1183].
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 8]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
2.7 Wildcard records
|
||||||
|
|
||||||
|
Wildcard MXs are useful mostly for non IP-connected sites. A common
|
||||||
|
mistake is thinking that a wildcard MX for a zone will apply to all
|
||||||
|
hosts in the zone. A wildcard MX will apply only to names in the
|
||||||
|
zone which aren't listed in the DNS at all. e.g.,
|
||||||
|
|
||||||
|
podunk.xx. IN NS ns1
|
||||||
|
IN NS ns2
|
||||||
|
mary IN A 1.2.3.4
|
||||||
|
*.podunk.xx. IN MX 5 sue
|
||||||
|
|
||||||
|
Mail for mary.podunk.xx will be sent to itself for delivery. Only
|
||||||
|
mail for jane.podunk.xx or any hosts you don't see above will be sent
|
||||||
|
to the MX. For most Internet sites, wildcard MX records are not
|
||||||
|
useful. You need to put explicit MX records on every host.
|
||||||
|
|
||||||
|
Wildcard MXs can be bad, because they make some operations succeed
|
||||||
|
when they should fail instead. Consider the case where someone in
|
||||||
|
the domain "widget.com" tries to send mail to "joe@larry". If the
|
||||||
|
host "larry" doesn't actually exist, the mail should in fact bounce
|
||||||
|
immediately. But because of domain searching the address gets
|
||||||
|
resolved to "larry.widget.com", and because of the wildcard MX this
|
||||||
|
is a valid address according to DNS. Or perhaps someone simply made
|
||||||
|
a typo in the hostname portion of the address. The mail message then
|
||||||
|
gets routed to the mail host, which then rejects the mail with
|
||||||
|
strange error messages like "I refuse to talk to myself" or "Local
|
||||||
|
configuration error".
|
||||||
|
|
||||||
|
Wildcard MX records are good for when you have a large number of
|
||||||
|
hosts which are not directly Internet-connected (for example, behind
|
||||||
|
a firewall) and for administrative or political reasons it is too
|
||||||
|
difficult to have individual MX records for every host, or to force
|
||||||
|
all e-mail addresses to be "hidden" behind one or more domain names.
|
||||||
|
In that case, you must divide your DNS into two parts, an internal
|
||||||
|
DNS, and an external DNS. The external DNS will have only a few
|
||||||
|
hosts and explicit MX records, and one or more wildcard MXs for each
|
||||||
|
internal domain. Internally the DNS will be complete, with all
|
||||||
|
explicit MX records and no wildcards.
|
||||||
|
|
||||||
|
Wildcard As and CNAMEs are possible too, and are really confusing to
|
||||||
|
users, and a potential nightmare if used without thinking first. It
|
||||||
|
could result (due again to domain searching) in any telnet/ftp
|
||||||
|
attempts from within the domain to unknown hosts to be directed to
|
||||||
|
one address. One such wildcard CNAME (in *.edu.com) caused
|
||||||
|
Internet-wide loss of services and potential security nightmares due
|
||||||
|
to unexpected interactions with domain searching. It resulted in
|
||||||
|
swift fixes, and even an RFC ([RFC 1535]) documenting the problem.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 9]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
2.8 Authority and Delegation Errors (NS records)
|
||||||
|
|
||||||
|
You are required to have at least two nameservers for every domain,
|
||||||
|
though more is preferred. Have secondaries outside your network. If
|
||||||
|
the secondary isn't under your control, periodically check up on them
|
||||||
|
and make sure they're getting current zone data from you. Queries to
|
||||||
|
their nameserver about your hosts should always result in an
|
||||||
|
"authoritative" response. If not, this is called a "lame
|
||||||
|
delegation". A lame delegations exists when a nameserver is
|
||||||
|
delegated responsibility for providing nameservice for a zone (via NS
|
||||||
|
records) but is not performing nameservice for that zone (usually
|
||||||
|
because it is not set up as a primary or secondary for the zone).
|
||||||
|
|
||||||
|
The "classic" lame delegation can be illustrated in this example:
|
||||||
|
|
||||||
|
podunk.xx. IN NS ns1.podunk.xx.
|
||||||
|
IN NS ns0.widget.com.
|
||||||
|
|
||||||
|
"podunk.xx" is a new domain which has recently been created, and
|
||||||
|
"ns1.podunk.xx" has been set up to perform nameservice for the zone.
|
||||||
|
They haven't quite finished everything yet and haven't made sure that
|
||||||
|
the hostmaster at "ns0.widget.com" has set up to be a proper
|
||||||
|
secondary, and thus has no information about the podunk.xx domain,
|
||||||
|
even though the DNS says it is supposed to. Various things can
|
||||||
|
happen depending on which nameserver is used. At best, extra DNS
|
||||||
|
traffic will result from a lame delegation. At worst, you can get
|
||||||
|
unresolved hosts and bounced e-mail.
|
||||||
|
|
||||||
|
Also, sometimes a nameserver is moved to another host or removed from
|
||||||
|
the list of secondaries. Unfortunately due to caching of NS records,
|
||||||
|
many sites will still think that a host is a secondary after that
|
||||||
|
host has stopped providing nameservice. In order to prevent lame
|
||||||
|
delegations while the cache is being aged, continue to provide
|
||||||
|
nameservice on the old nameserver for the length of the maximum of
|
||||||
|
the minimum plus refresh times for the zone and the parent zone.
|
||||||
|
(See section 2.2)
|
||||||
|
|
||||||
|
Whenever a primary or secondary is removed or changed, it takes a
|
||||||
|
fair amount of human coordination among the parties involved. (The
|
||||||
|
site itself, it's parent, and the site hosting the secondary) When a
|
||||||
|
primary moves, make sure all secondaries have their named.boot files
|
||||||
|
updated and their servers reloaded. When a secondary moves, make
|
||||||
|
sure the address records at both the primary and parent level are
|
||||||
|
changed.
|
||||||
|
|
||||||
|
It's also been reported that some distant sites like to pick popular
|
||||||
|
nameservers like "ns.uu.net" and just add it to their list of NS
|
||||||
|
records in hopes that they will magically perform additional
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 10]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
nameservice for them. This is an even worse form of lame delegation,
|
||||||
|
since this adds traffic to an already busy nameserver. Please
|
||||||
|
contact the hostmasters of sites which have lame delegations.
|
||||||
|
Various tools can be used to detect or actively find lame
|
||||||
|
delegations. See the list of contributed software in the BIND
|
||||||
|
distribution.
|
||||||
|
|
||||||
|
Make sure your parent domain has the same NS records for your zone as
|
||||||
|
you do. (Don't forget your in-addr.arpa zones too!). Do not list
|
||||||
|
too many (7 is the recommended maximum), as this just makes things
|
||||||
|
harder to manage and is only really necessary for very popular top-
|
||||||
|
level or root zones. You also run the risk of overflowing the 512-
|
||||||
|
byte limit of a UDP packet in the response to an NS query. If this
|
||||||
|
happens, resolvers will "fall back" to using TCP requests, resulting
|
||||||
|
in increased load on your nameserver.
|
||||||
|
|
||||||
|
It's important when picking geographic locations for secondary
|
||||||
|
nameservers to minimize latency as well as increase reliability.
|
||||||
|
Keep in mind network topologies. For example if your site is on the
|
||||||
|
other end of a slow local or international link, consider a secondary
|
||||||
|
on the other side of the link to decrease average latency. Contact
|
||||||
|
your Internet service provider or parent domain contact for more
|
||||||
|
information about secondaries which may be available to you.
|
||||||
|
|
||||||
|
3. BIND operation
|
||||||
|
|
||||||
|
This section discusses common problems people have in the actual
|
||||||
|
operation of the nameserver (specifically, BIND). Not only must the
|
||||||
|
data be correct as explained above, but the nameserver must be
|
||||||
|
operated correctly for the data to be made available.
|
||||||
|
|
||||||
|
3.1 Serial numbers
|
||||||
|
|
||||||
|
Each zone has a serial number associated with it. Its use is for
|
||||||
|
keeping track of who has the most current data. If and only if the
|
||||||
|
primary's serial number of the zone is greater will the secondary ask
|
||||||
|
the primary for a copy of the new zone data (see special case below).
|
||||||
|
|
||||||
|
Don't forget to change the serial number when you change data! If
|
||||||
|
you don't, your secondaries will not transfer the new zone
|
||||||
|
information. Automating the incrementing of the serial number with
|
||||||
|
software is also a good idea.
|
||||||
|
|
||||||
|
If you make a mistake and increment the serial number too high, and
|
||||||
|
you want to reset the serial number to a lower value, use the
|
||||||
|
following procedure:
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 11]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
Take the `incorrect' serial number and add 2147483647 to it. If
|
||||||
|
the number exceeds 4294967296, subtract 4294967296. Load the
|
||||||
|
resulting number. Then wait 2 refresh periods to allow the zone
|
||||||
|
to propagate to all servers.
|
||||||
|
|
||||||
|
Repeat above until the resulting serial number is less than the
|
||||||
|
target serial number.
|
||||||
|
|
||||||
|
Up the serial number to the target serial number.
|
||||||
|
|
||||||
|
This procedure won't work if one of your secondaries is running an
|
||||||
|
old version of BIND (4.8.3 or earlier). In this case you'll have to
|
||||||
|
contact the hostmaster for that secondary and have them kill the
|
||||||
|
secondary servers, remove the saved backup file, and restart the
|
||||||
|
server. Be careful when editing the serial number -- DNS admins
|
||||||
|
don't like to kill and restart nameservers because you lose all that
|
||||||
|
cached data.
|
||||||
|
|
||||||
|
3.2 Zone file style guide
|
||||||
|
|
||||||
|
Here are some useful tips in structuring your zone files. Following
|
||||||
|
these will help you spot mistakes, and avoid making more.
|
||||||
|
|
||||||
|
Be consistent with the style of entries in your DNS files. If your
|
||||||
|
$ORIGIN is podunk.xx., try not to write entries like:
|
||||||
|
|
||||||
|
mary IN A 1.2.3.1
|
||||||
|
sue.podunk.xx. IN A 1.2.3.2
|
||||||
|
|
||||||
|
or:
|
||||||
|
|
||||||
|
bobbi IN A 1.2.3.2
|
||||||
|
IN MX mary.podunk.xx.
|
||||||
|
|
||||||
|
|
||||||
|
Either use all FQDNs (Fully Qualified Domain Names) everywhere or
|
||||||
|
used unqualified names everywhere. Or have FQDNs all on the right-
|
||||||
|
hand side but unqualified names on the left. Above all, be
|
||||||
|
consistent.
|
||||||
|
|
||||||
|
Use tabs between fields, and try to keep columns lined up. It makes
|
||||||
|
it easier to spot missing fields (note some fields such as "IN" are
|
||||||
|
inherited from the previous record and may be left out in certain
|
||||||
|
circumstances.)
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 12]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
Remember you don't need to repeat the name of the host when you are
|
||||||
|
defining multiple records for one host. Be sure also to keep all
|
||||||
|
records associated with a host together in the file. It will make
|
||||||
|
things more straightforward when it comes time to remove or rename a
|
||||||
|
host.
|
||||||
|
|
||||||
|
Always remember your $ORIGIN. If you don't put a `.' at the end of
|
||||||
|
an FQDN, it's not recognized as an FQDN. If it is not an FQDN, then
|
||||||
|
the nameserver will append $ORIGIN to the name. Double check, triple
|
||||||
|
check, those trailing dots, especially in in-addr.arpa zone files,
|
||||||
|
where they are needed the most.
|
||||||
|
|
||||||
|
Be careful with the syntax of the SOA and WKS records (the records
|
||||||
|
which use parentheses). BIND is not very flexible in how it parses
|
||||||
|
these records. See the documentation for BIND.
|
||||||
|
|
||||||
|
3.3 Verifying data
|
||||||
|
|
||||||
|
Verify the data you just entered or changed by querying the resolver
|
||||||
|
with dig (or your favorite DNS tool, many are included in the BIND
|
||||||
|
distribution) after a change. A few seconds spent double checking
|
||||||
|
can save hours of trouble, lost mail, and general headaches. Also be
|
||||||
|
sure to check syslog output when you reload the nameserver. If you
|
||||||
|
have grievous errors in your DNS data or boot file, named will report
|
||||||
|
it via syslog.
|
||||||
|
|
||||||
|
It is also highly recommended that you automate this checking, either
|
||||||
|
with software which runs sanity checks on the data files before they
|
||||||
|
are loaded into the nameserver, or with software which checks the
|
||||||
|
data already loaded in the nameserver. Some contributed software to
|
||||||
|
do this is included in the BIND distribution.
|
||||||
|
|
||||||
|
4. Miscellaneous Topics
|
||||||
|
|
||||||
|
4.1 Boot file setup
|
||||||
|
|
||||||
|
Certain zones should always be present in nameserver configurations:
|
||||||
|
|
||||||
|
primary localhost localhost
|
||||||
|
primary 0.0.127.in-addr.arpa 127.0
|
||||||
|
primary 255.in-addr.arpa 255
|
||||||
|
primary 0.in-addr.arpa 0
|
||||||
|
|
||||||
|
These are set up to either provide nameservice for "special"
|
||||||
|
addresses, or to help eliminate accidental queries for broadcast or
|
||||||
|
local address to be sent off to the root nameservers. All of these
|
||||||
|
files will contain NS and SOA records just like the other zone files
|
||||||
|
you maintain, the exception being that you can probably make the SOA
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 13]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
timers very long, since this data will never change.
|
||||||
|
|
||||||
|
The "localhost" address is a "special" address which always refers to
|
||||||
|
the local host. It should contain the following line:
|
||||||
|
|
||||||
|
localhost. IN A 127.0.0.1
|
||||||
|
|
||||||
|
The "127.0" file should contain the line:
|
||||||
|
|
||||||
|
1 PTR localhost.
|
||||||
|
|
||||||
|
There has been some extensive discussion about whether or not to
|
||||||
|
append the local domain to it. The conclusion is that "localhost."
|
||||||
|
would be the best solution. The reasons given include:
|
||||||
|
|
||||||
|
"localhost" by itself is used and expected to work in some
|
||||||
|
systems.
|
||||||
|
|
||||||
|
Translating 127.0.0.1 into "localhost.dom.ain" can cause some
|
||||||
|
software to connect back to the loopback interface when it didn't
|
||||||
|
want to because "localhost" is not equal to "localhost.dom.ain".
|
||||||
|
|
||||||
|
The "255" and "0" files should not contain any additional data beyond
|
||||||
|
the NS and SOA records.
|
||||||
|
|
||||||
|
Note that future BIND versions may include all or some of this data
|
||||||
|
automatically without additional configuration.
|
||||||
|
|
||||||
|
4.2 Other Resolver and Server bugs
|
||||||
|
|
||||||
|
Very old versions of the DNS resolver have a bug that cause queries
|
||||||
|
for names that look like IP addresses to go out, because the user
|
||||||
|
supplied an IP address and the software didn't realize that it didn't
|
||||||
|
need to be resolved. This has been fixed but occasionally it still
|
||||||
|
pops up. It's important because this bug means that these queries
|
||||||
|
will be sent directly to the root nameservers, adding to an already
|
||||||
|
heavy DNS load.
|
||||||
|
|
||||||
|
While running a secondary nameserver off another secondary nameserver
|
||||||
|
is possible, it is not recommended unless necessary due to network
|
||||||
|
topologies. There are known cases where it has led to problems like
|
||||||
|
bogus TTL values. While this may be caused by older or flawed DNS
|
||||||
|
implementations, you should not chain secondaries off of one another
|
||||||
|
since this builds up additional reliability dependencies as well as
|
||||||
|
adds additional delays in updates of new zone data.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 14]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
4.3 Server issues
|
||||||
|
|
||||||
|
DNS operates primarily via UDP (User Datagram Protocol) messages.
|
||||||
|
Some UNIX operating systems, in an effort to save CPU cycles, run
|
||||||
|
with UDP checksums turned off. The relative merits of this have long
|
||||||
|
been debated. However, with the increase in CPU speeds, the
|
||||||
|
performance considerations become less and less important. It is
|
||||||
|
strongly encouraged that you turn on UDP checksumming to avoid
|
||||||
|
corrupted data not only with DNS but with other services that use UDP
|
||||||
|
(like NFS). Check with your operating system documentation to verify
|
||||||
|
that UDP checksumming is enabled.
|
||||||
|
|
||||||
|
References
|
||||||
|
|
||||||
|
[RFC 974] Partridge, C., "Mail routing and the domain system", STD
|
||||||
|
14, RFC 974, CSNET CIC BBN Laboratories Inc, January 1986.
|
||||||
|
|
||||||
|
[RFC 1033] Lottor, M, "Domain Administrators Operations Guide", RFC
|
||||||
|
1033, USC/Information Sciences Institute, November 1987.
|
||||||
|
|
||||||
|
[RFC 1034] Mockapetris, P., "Domain Names - Concepts and Facilities",
|
||||||
|
STD 13, RFC 1034, USC/Information Sciences Institute,
|
||||||
|
November 1987.
|
||||||
|
|
||||||
|
[RFC 1035] Mockapetris, P., "Domain Names - Implementation and
|
||||||
|
Specification", STD 13, RFC 1035, USC/Information Sciences
|
||||||
|
Institute, November 1987.
|
||||||
|
|
||||||
|
[RFC 1123] Braden, R., "Requirements for Internet Hosts --
|
||||||
|
Application and Support", STD 3, RFC 1123, IETF, October
|
||||||
|
1989.
|
||||||
|
|
||||||
|
[RFC 1178] Libes, D., "Choosing a Name for Your Computer", FYI 5, RFC
|
||||||
|
1178, Integrated Systems Group/NIST, August 1990.
|
||||||
|
|
||||||
|
[RFC 1183] Ullman, R., Mockapetris, P., Mamakos, L, and C. Everhart,
|
||||||
|
"New DNS RR Definitions", RFC 1183, October 1990.
|
||||||
|
|
||||||
|
[RFC 1535] Gavron, E., "A Security Problem and Proposed Correction
|
||||||
|
With Widely Deployed DNS Software", RFC 1535, ACES
|
||||||
|
Research Inc., October 1993.
|
||||||
|
|
||||||
|
[RFC 1536] Kumar, A., Postel, J., Neuman, C., Danzig, P., and S.
|
||||||
|
Miller, "Common DNS Implementation Errors and Suggested
|
||||||
|
Fixes", RFC 1536, USC/Information Sciences Institute, USC,
|
||||||
|
October 1993.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 15]
|
||||||
|
|
||||||
|
RFC 1912 Common DNS Errors February 1996
|
||||||
|
|
||||||
|
|
||||||
|
[RFC 1537] Beertema, P., "Common DNS Data File Configuration Errors",
|
||||||
|
RFC 1537, CWI, October 1993.
|
||||||
|
|
||||||
|
[RFC 1713] A. Romao, "Tools for DNS debugging", RFC 1713, FCCN,
|
||||||
|
November 1994.
|
||||||
|
|
||||||
|
[BOG] Vixie, P, et. al., "Name Server Operations Guide for BIND",
|
||||||
|
Vixie Enterprises, July 1994.
|
||||||
|
|
||||||
|
5. Security Considerations
|
||||||
|
|
||||||
|
Security issues are not discussed in this memo.
|
||||||
|
|
||||||
|
6. Author's Address
|
||||||
|
|
||||||
|
David Barr
|
||||||
|
The Pennsylvania State University
|
||||||
|
Department of Mathematics
|
||||||
|
334 Whitmore Building
|
||||||
|
University Park, PA 16802
|
||||||
|
|
||||||
|
Voice: +1 814 863 7374
|
||||||
|
Fax: +1 814 863-8311
|
||||||
|
EMail: barr@math.psu.edu
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Barr Informational [Page 16]
|
||||||
|
|
||||||
28
dns/dnswalk/sendreports
Executable file
28
dns/dnswalk/sendreports
Executable file
|
|
@ -0,0 +1,28 @@
|
||||||
|
#!/bin/sh
|
||||||
|
DATE=`date +%m/%y`
|
||||||
|
for file in *; do
|
||||||
|
hostmaster=`echo $file | sed 's/\./@/'`
|
||||||
|
echo Sending report to "$hostmaster"
|
||||||
|
(
|
||||||
|
cat <<EOF
|
||||||
|
The following is a report made by the 'dnswalk' program for the DNS
|
||||||
|
data under your control. You are getting this report because dnswalk
|
||||||
|
found potential errors in your DNS. Please refer to the following
|
||||||
|
explanations of the error messages and why they are important and make
|
||||||
|
the necessary corrections to your DNS.
|
||||||
|
|
||||||
|
If you would like a more extended discussion of common mistakes people
|
||||||
|
make in setting up and running a DNS server, see RFC 1912 at
|
||||||
|
ftp.internic.net:/rfc/rfc1912.txt
|
||||||
|
|
||||||
|
If you would like the source to the program which generates this
|
||||||
|
data, you can get it at http://www.cis.ohio-state.edu/~barr/dnswalk/
|
||||||
|
|
||||||
|
EOF
|
||||||
|
cat ../dnswalk.errors;\
|
||||||
|
echo "";\
|
||||||
|
cat $file;\
|
||||||
|
) | /usr/ucb/Mail -s "DNS error report for $DATE" $hostmaster
|
||||||
|
# ) | cat >/tmp/reports/$file
|
||||||
|
sleep 1
|
||||||
|
done
|
||||||
8
dns/scripts/README.md
Normal file
8
dns/scripts/README.md
Normal file
|
|
@ -0,0 +1,8 @@
|
||||||
|
# axfr
|
||||||
|
Get the nameserver (if specified) and set up the zone transfer
|
||||||
|
|
||||||
|
# ghba.c
|
||||||
|
Scan DNS Zones/Networks
|
||||||
|
|
||||||
|
# netdns.pl
|
||||||
|
Script to do bulk PTR lookups on a network of IP's
|
||||||
183
dns/scripts/axfr
Executable file
183
dns/scripts/axfr
Executable file
|
|
@ -0,0 +1,183 @@
|
||||||
|
#!/usr/bin/perl -w
|
||||||
|
# $Id: axfr 264 2005-04-06 09:16:15Z olaf $
|
||||||
|
|
||||||
|
use strict;
|
||||||
|
use vars qw($opt_f $opt_q $opt_s $opt_D);
|
||||||
|
use File::Basename;
|
||||||
|
use Getopt::Std;
|
||||||
|
use Net::DNS;
|
||||||
|
use Storable;
|
||||||
|
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
# Read any command-line options and check syntax.
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
getopts("fqsD:");
|
||||||
|
|
||||||
|
die "Usage: ", basename($0), " [ -fqs ] [ -D directory ] [ \@nameserver ] zone\n"
|
||||||
|
unless (@ARGV >= 1) && (@ARGV <= 2);
|
||||||
|
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
# Get the nameserver (if specified) and set up the zone transfer directory
|
||||||
|
# hierarchy.
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
my $nameserver = ($ARGV[0] =~ /^@/) ? shift @ARGV : "";
|
||||||
|
$nameserver =~ s/^@//;
|
||||||
|
|
||||||
|
my $zone = shift @ARGV;
|
||||||
|
my $basedir = defined $opt_D ? $opt_D : $ENV{"HOME"} . "/.dns-zones";
|
||||||
|
my $zonedir = join("/", reverse(split(/\./, $zone)));
|
||||||
|
my $zonefile = $basedir . "/" . $zonedir . "/axfr";
|
||||||
|
|
||||||
|
# Don't worry about the 0777 permissions here - the current umask setting
|
||||||
|
# will be applied.
|
||||||
|
unless (-d $basedir) {
|
||||||
|
mkdir($basedir, 0777) or die "can't mkdir $basedir: $!\n";
|
||||||
|
}
|
||||||
|
|
||||||
|
my $dir = $basedir;
|
||||||
|
my $subdir;
|
||||||
|
foreach $subdir (split(m#/#, $zonedir)) {
|
||||||
|
$dir .= "/" . $subdir;
|
||||||
|
unless (-d $dir) {
|
||||||
|
mkdir($dir, 0777) or die "can't mkdir $dir: $!\n";
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
# Get the zone.
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
my $res = Net::DNS::Resolver->new;
|
||||||
|
$res->nameservers($nameserver) if $nameserver;
|
||||||
|
|
||||||
|
my (@zone, $zoneref);
|
||||||
|
|
||||||
|
if (-e $zonefile && !defined $opt_f) {
|
||||||
|
$zoneref = retrieve($zonefile) || die "couldn't retrieve zone from $zonefile: $!\n";
|
||||||
|
|
||||||
|
#----------------------------------------------------------------------
|
||||||
|
# Check the SOA serial number if desired.
|
||||||
|
#----------------------------------------------------------------------
|
||||||
|
|
||||||
|
if (defined $opt_s) {
|
||||||
|
my($serial_file, $serial_zone);
|
||||||
|
|
||||||
|
my $rr;
|
||||||
|
foreach $rr (@$zoneref) {
|
||||||
|
if ($rr->type eq "SOA") {
|
||||||
|
$serial_file = $rr->serial;
|
||||||
|
last;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
die "no SOA in $zonefile\n" unless defined $serial_file;
|
||||||
|
|
||||||
|
my $soa = $res->query($zone, "SOA");
|
||||||
|
die "couldn't get SOA for $zone: ", $res->errorstring, "\n"
|
||||||
|
unless defined $soa;
|
||||||
|
|
||||||
|
foreach $rr ($soa->answer) {
|
||||||
|
if ($rr->type eq "SOA") {
|
||||||
|
$serial_zone = $rr->serial;
|
||||||
|
last;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if ($serial_zone != $serial_file) {
|
||||||
|
$opt_f = 1;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
$opt_f = 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (defined $opt_f) {
|
||||||
|
@zone = $res->axfr($zone);
|
||||||
|
die "couldn't transfer zone: ", $res->errorstring, "\n" unless @zone;
|
||||||
|
store \@zone, $zonefile or die "couldn't store zone to $zonefile: $!\n";
|
||||||
|
$zoneref = \@zone;
|
||||||
|
}
|
||||||
|
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
# Print the records in the zone.
|
||||||
|
#------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
unless ($opt_q) {
|
||||||
|
$_->print for @$zoneref
|
||||||
|
}
|
||||||
|
|
||||||
|
__END__
|
||||||
|
|
||||||
|
=head1 NAME
|
||||||
|
|
||||||
|
axfr - Perform a DNS zone transfer
|
||||||
|
|
||||||
|
=head1 SYNOPSIS
|
||||||
|
|
||||||
|
B<axfr> S<[ B<-fqs> ]> S<[ B<-D> I<directory> ]> S<[ B<@>I<nameserver> ]>
|
||||||
|
I<zone>
|
||||||
|
|
||||||
|
=head1 DESCRIPTION
|
||||||
|
|
||||||
|
B<axfr> performs a DNS zone transfer, prints each record to the standard
|
||||||
|
output, and stores the zone to a file. If the zone has already been
|
||||||
|
stored in a file, B<axfr> will read the file instead of performing a
|
||||||
|
zone transfer.
|
||||||
|
|
||||||
|
Zones will be stored in a directory hierarchy. For example, the
|
||||||
|
zone transfer for foo.bar.com will be stored in the file
|
||||||
|
$HOME/.dns-zones/com/bar/foo/axfr. The directory can be changed
|
||||||
|
with the B<-D> option.
|
||||||
|
|
||||||
|
This programs requires that the Storable module be installed.
|
||||||
|
|
||||||
|
=head1 OPTIONS
|
||||||
|
|
||||||
|
=over 4
|
||||||
|
|
||||||
|
=item B<-f>
|
||||||
|
|
||||||
|
Force a zone transfer, even if the zone has already been stored
|
||||||
|
in a file.
|
||||||
|
|
||||||
|
=item B<-q>
|
||||||
|
|
||||||
|
Be quiet -- don't print the records from the zone.
|
||||||
|
|
||||||
|
=item B<-s>
|
||||||
|
|
||||||
|
Perform a zone transfer if the SOA serial number on the nameserver
|
||||||
|
is different than the serial number in the zone file.
|
||||||
|
|
||||||
|
=item B<-D> I<directory>
|
||||||
|
|
||||||
|
Store zone files under I<directory> instead of the default directory
|
||||||
|
(see L<"FILES">).
|
||||||
|
|
||||||
|
=item B<@>I<nameserver>
|
||||||
|
|
||||||
|
Query I<nameserver> instead of the default nameserver.
|
||||||
|
|
||||||
|
=back
|
||||||
|
|
||||||
|
=head1 FILES
|
||||||
|
|
||||||
|
=over 4
|
||||||
|
|
||||||
|
=item B<$HOME/.dns-zones>
|
||||||
|
|
||||||
|
Default directory for storing zone files.
|
||||||
|
|
||||||
|
=back
|
||||||
|
|
||||||
|
=head1 AUTHOR
|
||||||
|
|
||||||
|
Michael Fuhr <mike@fuhr.org>
|
||||||
|
|
||||||
|
=head1 SEE ALSO
|
||||||
|
|
||||||
|
L<perl(1)>, L<check_soa>, L<check_zone>, L<mresolv>, L<mx>, L<perldig>,
|
||||||
|
L<Net::DNS>, L<Storable>
|
||||||
|
|
||||||
|
=cut
|
||||||
221
dns/scripts/ghba.c
Executable file
221
dns/scripts/ghba.c
Executable file
|
|
@ -0,0 +1,221 @@
|
||||||
|
/*
|
||||||
|
* k0pyR1ght (c) 1994 [l0ck] The l3g3ntz 0f c0de k1dZZzz
|
||||||
|
* aWl rYt3z r3-z3rvd!!@#!@#!@#!@#$!@
|
||||||
|
* aWL b3l0w k0mp0zed bY gw33d0 s4nch3z wh0z3 3g0 d1ktAytEz d1z kr3d1t.
|
||||||
|
*
|
||||||
|
* 411 k0de 1z d-rYv3d 4n 0bt41nD fr0m d4 m0thah-luV1n 4ur4 0f e1ytneZz
|
||||||
|
* th4t s00r0undZZz d4 h0ly l0ck cHyld 0f d4 v1rg1n 4k4shA E.I.
|
||||||
|
*
|
||||||
|
* r3-d1sTriby00shUn 4n y00ze 4n sh1t 1n s0urce, b1n4ry, 4n pGp'd ph0rmz,
|
||||||
|
* w1t 0 w1t0ut m0d1f1-k-shUnz n sh1t, r p3r-m1ttd pr0-vYd3d d4t d4
|
||||||
|
* ph0ll0w1n k0nd1shUnz 1z m3t n sh1t:
|
||||||
|
* 1. y00 muZt re-tAyn d1s h3r3 k0pyR1gh gn0t1c3. 1f y00 r3m00v3 1t,
|
||||||
|
* w3 w1ll hunt d0wn y0 m0mma, ty3 h3r 2 d4 n0rth w4ll (rWa[1]1) 0f
|
||||||
|
* d4 l0ck-hauz 4n r33ch n 4n r1p 0ut h3r y00terUz 2 sp4r3 fy00tUre
|
||||||
|
* g3n3rashUnz fr0m th3 un-3lytn3zZZz 0f n-e-m0r3 0f h3r d3m0nSp4wn.
|
||||||
|
* 0h yah. w3'll kall da sp4 n sh1t t00.
|
||||||
|
* 2. aWl adv3rt1z1ng m4t3r1alz m3nShun1n ph33ty00rez 0r y00ze 0f d1z
|
||||||
|
* h3r3 s0phtw4r3 mUzt d1spl4y d4 f0ll0w1ng ak47n0wl3dgem3nt:
|
||||||
|
*
|
||||||
|
* gn0t1c3:
|
||||||
|
* th1s h3r3 pr0dUkt 1z s00p33r10r 2 n-3 p33c3 0f sh1t y00 k0uld 3v4h
|
||||||
|
* kr4nk 0ut w1t y0 4-b1t l0g0 k0mpYl3r. Ph33r, laYm00rzZz!!@#!@#$
|
||||||
|
*
|
||||||
|
* 3. y00 mUzt nAym3 y0' f1rstb0rn K4rl 0r n-3 4n4gr4m th3r30f.
|
||||||
|
* 4. th3 1mag3 0f l4rry l0ck, d3 l0ck l0g0, 4n 1nd33d d4 l3tt3rz l, c,
|
||||||
|
* k m4y gn0t b3 y00zed 2 3nd0rz3 0r pr0m0t3 pr0dux d-rYv3d fr0m d1s
|
||||||
|
* h3r3 3lyt ph33t 0f pr0gr4mm1ng w1t0ut g1v1n s4rl0 h3d.
|
||||||
|
*
|
||||||
|
* d1s s0phTw4r3 1z pr0vYd3d "az 1z" fr0m d4 k0ll3kt1v3 l3g10nz d4t maYk3
|
||||||
|
* uP l0ck. y00 0wn d1s s0fwAYre 4 a r33z0n. d0n't th1nk y00 h4qd 0n3 0f
|
||||||
|
* 0ur akk0untz n sNaYtch3d a pr1m0 0-d4y l0ckw4r3; w3 pl4nt3d d1z 4Wn
|
||||||
|
* pUrp0z3 b-kuz w3 g0t p1ty f0 y0 layme a$$. 1n gn0 3v3nt sh4ll w3, l0ck,
|
||||||
|
* b3 h3ld l1abl3 f0r da L4yMen3zz 0f th3 sh1t y00 h4q 0ut 0f th1z fUx1n
|
||||||
|
* 3lyt k0de. d0n't ch4Yng3 1t kUz 1tz aWlr3dY b3ttah th3n y00 k00d 3vah
|
||||||
|
* wr1t3, j00. bUt 1f y00 d0, d0n't kUm kry1n 2 Uz 2 g1v3 y00 d4 0r1g1n4l
|
||||||
|
* kUz y00 w3nt n 4dd3d 4n 0n-skr33n kl0k r sUm laYme sh1t n 1t fuxd Up
|
||||||
|
* d n-tYr3 pr0gr4m. 1ph d1z h4pp3nz, w3, d4 p4rt33z m3nshUnned ab0ve,
|
||||||
|
* k0ns1gn y00 t0 l0k4l layMur h3ll; 4n e-tUrn1t33 0f k4ll1ng WW1v Ad00lt
|
||||||
|
* p0rn0gr4ffy SiTEzZzz n sh1t. w3 gair-N-t33 gn0th1ng bUt 0ur 3lytn3zz
|
||||||
|
* 4n y0' laYmen3zz. l3t d4 k0dezZz b3g1n, j00d3n!@#!@#$!@$!@#$!@#$
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef lint
|
||||||
|
char copyright[] =
|
||||||
|
"@(#) Copyright (c) 1994, 1992 L3gi0n 0F c0d3 Kid3zz.\n\
|
||||||
|
All rights reserved.\n";
|
||||||
|
static char sccsid[] = "@(#)ghba.c 3.0 8/25/94 (l0ck)";
|
||||||
|
static char rcsid[] = "$Id: ghba.c, v3.0 1994/08/25 00:03:12 max-q Exp $";
|
||||||
|
#endif /* not lint */
|
||||||
|
|
||||||
|
/*
|
||||||
|
* no time for sarcasm... the kideez would take it seriously, anyway.
|
||||||
|
* you don't need to supply a switch for an address type... either the
|
||||||
|
* full address or a netmask will work just fine.
|
||||||
|
*
|
||||||
|
* the only switches left are:
|
||||||
|
* x - address provided is in hexadecimal
|
||||||
|
* a - show hostname aliases also
|
||||||
|
* f - output to a file and background the process
|
||||||
|
*
|
||||||
|
* max-q
|
||||||
|
*/
|
||||||
|
|
||||||
|
#include <stdio.h>
|
||||||
|
#include <fcntl.h>
|
||||||
|
#include <sys/types.h>
|
||||||
|
#include <sys/socket.h>
|
||||||
|
#include <sys/ioctl.h>
|
||||||
|
#include "netdb.h"
|
||||||
|
|
||||||
|
#define S_HEX "%x.%x.%x.%x"
|
||||||
|
#define S_DEC "%d.%d.%d.%d"
|
||||||
|
|
||||||
|
void
|
||||||
|
bad_addr(addr)
|
||||||
|
int addr;
|
||||||
|
{
|
||||||
|
fprintf(stderr, "Value %d is not valid.\n", addr);
|
||||||
|
exit(-1);
|
||||||
|
}
|
||||||
|
|
||||||
|
void
|
||||||
|
check_addr(addr)
|
||||||
|
int addr[];
|
||||||
|
{
|
||||||
|
register int i;
|
||||||
|
for(i=0;i<4;i++)
|
||||||
|
if(addr[i]<0||addr[i]>255)
|
||||||
|
bad_addr(addr[i]);
|
||||||
|
}
|
||||||
|
|
||||||
|
void
|
||||||
|
usage(name)
|
||||||
|
int *name;
|
||||||
|
{
|
||||||
|
fprintf(stderr,
|
||||||
|
"usage: %s [-x] [-a] [-f <outfile>] aaa.bbb.[ccc||0].[ddd||0]\n",
|
||||||
|
name);
|
||||||
|
exit(-1);
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
void
|
||||||
|
main(argc, argv)
|
||||||
|
int argc;
|
||||||
|
char *argv[];
|
||||||
|
{
|
||||||
|
char addr[4], **ptr,
|
||||||
|
*progname = argv[0];
|
||||||
|
register int s;
|
||||||
|
int a[4], arg, c, d,
|
||||||
|
classB, classC, single,
|
||||||
|
alias, hex, file;
|
||||||
|
extern char *optarg;
|
||||||
|
struct hostent *host,
|
||||||
|
*gethostbyaddr();
|
||||||
|
FILE *outfd = stdout;
|
||||||
|
|
||||||
|
classB = classC = single = alias = hex = file = 0;
|
||||||
|
c = d = 0;
|
||||||
|
|
||||||
|
while((arg = getopt(argc, argv, "xaf:")) != EOF) {
|
||||||
|
switch(arg) {
|
||||||
|
case 'x':
|
||||||
|
hex++;
|
||||||
|
break;
|
||||||
|
case 'a':
|
||||||
|
alias++;
|
||||||
|
break;
|
||||||
|
case 'f':
|
||||||
|
file++;
|
||||||
|
if((outfd=fopen(optarg, "a"))==NULL) {
|
||||||
|
perror("open");
|
||||||
|
exit(-1);
|
||||||
|
}
|
||||||
|
break;
|
||||||
|
default:
|
||||||
|
usage(progname);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
argv += ((file)?2:0)+((alias)?1:0)+((hex)?1:0);
|
||||||
|
argc -= ((file)?2:0)+((alias)?1:0)+((hex)?1:0);
|
||||||
|
|
||||||
|
if(argc!=2)
|
||||||
|
usage(progname);
|
||||||
|
|
||||||
|
sscanf(argv[1], (hex)?S_HEX:S_DEC, &a[0], &a[1], &a[2], &a[3]);
|
||||||
|
|
||||||
|
check_addr(a);
|
||||||
|
|
||||||
|
if(!a[3]) {
|
||||||
|
if(!a[2])
|
||||||
|
classB++;
|
||||||
|
else
|
||||||
|
classC++;
|
||||||
|
} else
|
||||||
|
single++;
|
||||||
|
|
||||||
|
if(!classB && !classC && !single)
|
||||||
|
usage(progname);
|
||||||
|
|
||||||
|
if(file) {
|
||||||
|
if((s=fork()) >0) {
|
||||||
|
fprintf(stderr, "[%s - pid %d]\n", progname, s);
|
||||||
|
exit(0);
|
||||||
|
} else if(s<0) {
|
||||||
|
perror("fork");
|
||||||
|
exit(-1);
|
||||||
|
}
|
||||||
|
|
||||||
|
if((s=open("/dev/tty", O_RDWR)) >0) {
|
||||||
|
ioctl(s, TIOCNOTTY, (char *) NULL);
|
||||||
|
close(s);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
addr[0] = (unsigned char) a[0];
|
||||||
|
addr[1] = (unsigned char) a[1];
|
||||||
|
|
||||||
|
if(classC)
|
||||||
|
goto jmpC;
|
||||||
|
else if(single)
|
||||||
|
goto jmpS;
|
||||||
|
|
||||||
|
fprintf(((file)?outfd:stderr), "Scanning Class B network %d.%d...\n",
|
||||||
|
a[0], a[1]);
|
||||||
|
|
||||||
|
while(c<256) {
|
||||||
|
a[2] = c++;
|
||||||
|
d = 0;
|
||||||
|
jmpC:
|
||||||
|
fprintf(((file)?outfd:stderr), "Scanning Class C network %d.%d.%d...\n",
|
||||||
|
a[0], a[1], a[2]);
|
||||||
|
|
||||||
|
while(d<256) {
|
||||||
|
a[3] = d++;
|
||||||
|
jmpS:
|
||||||
|
addr[2] = (unsigned char) a[2];
|
||||||
|
addr[3] = (unsigned char) a[3];
|
||||||
|
|
||||||
|
if((host = gethostbyaddr(addr, 4, AF_INET)) != NULL) {
|
||||||
|
fprintf(outfd, "%d.%d.%d.%d => %s\n", a[0], a[1], a[2], a[3], host->h_name);
|
||||||
|
|
||||||
|
ptr = host->h_aliases;
|
||||||
|
if(alias)
|
||||||
|
while(*ptr != NULL) {
|
||||||
|
fprintf(outfd, "%d.%d.%d.%d => %s (alias)\n",
|
||||||
|
a[0], a[1], a[2], a[3], *ptr);
|
||||||
|
ptr++;
|
||||||
|
}
|
||||||
|
|
||||||
|
fflush(outfd);
|
||||||
|
if(single) exit(0);
|
||||||
|
} else if(single) {
|
||||||
|
fprintf(stderr, "Cannot resolve %d.%d.%d.%d\n", a[0], a[1], a[2], a[3]); exit(0);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
if(classC) exit(0);
|
||||||
|
}
|
||||||
|
}
|
||||||
Loading…
Add table
Add a link
Reference in a new issue