Net::DNS::Nameserver - DNS server class


Net::DNS::Nameserver - DNS server class


use Net::DNS::Nameserver;


Instances of the Net::DNS::Nameserver class represent simple DNS server objects. See EXAMPLE for an example.



 my $ns = Net::DNS::Nameserver->new(
        LocalAddr        => "",
        LocalPort        => "5353",
        ReplyHandler => \&reply_handler,
        Verbose          => 1

Creates a nameserver object. Attributes are:

  LocalAddr             IP address on which to listen.  Defaults to INADDR_ANY.
  LocalPort             Port on which to listen.  Defaults to 53.
  ReplyHandler  Reference to reply-handling subroutine.  Required.
  Verbose               Print info about received queries.      Defaults to 0 (off).

The ReplyHandler subroutine is passed the query name, query class, query type and optionally an argument containing header bit settings (see below). It must return the response code and references to the answer, authority, and additional sections of the response. Common response codes are:

  NOERROR       No error
  FORMERR       Format error
  SERVFAIL      Server failure
  NXDOMAIN      Non-existent domain (name doesn't exist)
  NOTIMP        Not implemented
  REFUSED       Query refused

For advanced usage there is an optional argument containing an hashref with the settings for the aa, ra, and ad header bits. The argument is of the form { ad => 1, aa => 0, ra => 1 }.

See RFC 1035 and the IANA dns-parameters file for more information:

The nameserver will listen for both UDP and TCP connections. On Unix-like systems, the program will probably have to run as root to listen on the default port, 53. A non-privileged user should be able to listen on ports 1024 and higher.

Returns a Net::DNS::Nameserver object, or undef if the object couldn't be created.

See EXAMPLE for an example.



Start accepting queries.


The following example will listen on port 5353 and respond to all queries for A records with the IP address All other queries will be answered with NXDOMAIN. Authority and additional sections are left empty. The $peerhost variable catches the IP address of the peer host, so that additional filtering on its basis may be applied.


 use Net::DNS;
 use strict;
 use warnings;

 sub reply_handler {
         my ($qname, $qclass, $qtype, $peerhost) = @_;
         my ($rcode, @ans, @auth, @add);

         if ($qtype eq "A") {
                 my ($ttl, $rdata) = (3600, "");
                 push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
                 $rcode = "NOERROR";
         } else {
         $rcode = "NXDOMAIN";

         # mark the answer as authoritive (by setting the 'aa' flag
         return ($rcode, \@ans, \@auth, \@add, { aa => 1 });

 my $ns = Net::DNS::Nameserver->new(
     LocalPort    => 5353,
     ReplyHandler => \&reply_handler,
     Verbose      => 1,
 ) || die "couldn't create nameserver object\n";


=head1 BUGS

Net::DNS::Nameserver objects can handle only one query at a time.


Copyright (c) 1997-2002 Michael Fuhr.

Portions Copyright (c) 2002-2004 Chris Reinhardt.

All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.


perl(1), the Net::DNS manpage, the Net::DNS::Resolver manpage, the Net::DNS::Packet manpage, the Net::DNS::Update manpage, the Net::DNS::Header manpage, the Net::DNS::Question manpage, the Net::DNS::RR manpage, RFC 1035

 Net::DNS::Nameserver - DNS server class