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#!/usr/bin/perl -w
# $Id: check_zone,v 1.6 2000/11/10 16:02:20 mfuhr Exp mfuhr $
=head1 NAME
check_zone - Check a DNS zone for errors
=head1 SYNOPSIS
C<check_zone> [ C<-r> ] I<domain> [ I<class> ]
=head1 DESCRIPTION
Checks a DNS zone for errors. Current checks are:
=over 4
=item *
Checks that all A records have corresponding PTR records.
=item *
Checks that hosts listed in NS, MX, and CNAME records have
A records.
=back
=head1 OPTIONS
=over 4
=item C<-r>
Perform a recursive check on subdomains.
=back
=head1 AUTHOR
Michael Fuhr <mike@fuhr.org>
=head1 SEE ALSO
L<perl(1)>, L<axfr>, L<check_soa>, L<mresolv>, L<mx>, L<perldig>, L<Net::DNS>
=cut
use strict;
use vars qw($opt_r);
use Getopt::Std;
use File::Basename;
use IO::Socket;
use Net::DNS;
getopts("r");
die "Usage: ", basename($0), " [ -r ] domain [ class ]\n"
unless (@ARGV >= 1) && (@ARGV <= 2);
check_domain(@ARGV);
exit;
sub check_domain {
my ($domain, $class) = @_;
$class ||= "IN";
print "-" x 70, "\n";
print "$domain (class $class)\n";
print "\n";
my $res = Net::DNS::Resolver->new;
$res->defnames(0);
$res->retry(2);
my $nspack = $res->query($domain, "NS", $class);
unless (defined($nspack)) {
warn "Couldn't find nameservers for $domain: ",
$res->errorstring, "\n";
return;
}
print "nameservers (will request zone from first available):\n";
my $ns;
foreach $ns (grep { $_->type eq "NS" } $nspack->answer) {
print "\t", $ns->nsdname, "\n";
}
print "\n";
$res->nameservers(map { $_->nsdname }
grep { $_->type eq "NS" }
$nspack->answer);
my @zone = $res->axfr($domain, $class);
unless (@zone) {
warn "Zone transfer failed: ", $res->errorstring, "\n";
return;
}
print "checking PTR records\n";
check_ptr($domain, $class, @zone);
print "\n";
print "checking NS records\n";
check_ns($domain, $class, @zone);
print "\n";
print "checking MX records\n";
check_mx($domain, $class, @zone);
print "\n";
print "checking CNAME records\n";
check_cname($domain, $class, @zone);
print "\n";
if ($opt_r) {
print "checking subdomains\n\n";
my %subdomains;
foreach (grep { $_->type eq "NS" and $_->name ne $domain } @zone) {
$subdomains{$_->name} = 1;
}
foreach (sort keys %subdomains) {
check_domain($_, $class);
}
}
}
sub check_ptr {
my ($domain, $class, @zone) = @_;
my $res = Net::DNS::Resolver->new;
my $rr;
foreach $rr (grep { $_->type eq "A" } @zone) {
my $host = $rr->name;
my $addr = $rr->address;
my $ans = $res->send($addr, "A", $class);
print "\t$host ($addr) has no PTR record\n"
if ($ans->header->ancount < 1);
}
}
sub check_ns {
my ($domain, $class, @zone) = @_;
my $res = Net::DNS::Resolver->new;
my $rr;
foreach $rr (grep { $_->type eq "NS" } @zone) {
my $ans = $res->send($rr->nsdname, "A", $class);
print "\t", $rr->nsdname, " has no A record\n"
if ($ans->header->ancount < 1);
}
}
sub check_mx {
my ($domain, $class, @zone) = @_;
my $res = Net::DNS::Resolver->new;
my $rr;
foreach $rr (grep { $_->type eq "MX" } @zone) {
my $ans = $res->send($rr->exchange, "A", $class);
print "\t", $rr->exchange, " has no A record\n"
if ($ans->header->ancount < 1);
}
}
sub check_cname {
my ($domain, $class, @zone) = @_;
my $res = Net::DNS::Resolver->new;
my $rr;
foreach $rr (grep { $_->type eq "CNAME" } @zone) {
my $ans = $res->send($rr->cname, "A", $class);
print "\t", $rr->cname, " has no A record\n"
if ($ans->header->ancount < 1);
}
}
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