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Man Pages


Manual Reference Pages  -  TIE::DNS (3)

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NAME

Tie::DNS - Tie interface to Net::DNS

CONTENTS

SYNOPSIS



    use Tie::DNS;

    tie my %dns, Tie::DNS;

    print "$dns{foo.bar.com}\n";

    print "$dns{208.180.41.1}\n";



DESCRIPTION

Net::DNS is a very complete, extensive and well-written module. It’s completeness, however, makes many comman cases uses a bit wordy, code-wise. Tie::DNS is meant to make common DNS operations trivial, and more complex DNS operations easier.

EXAMPLES

    Forward lookup

See Above.

    Zone transfer

Get all of the A records from ’foo.com’. (Sorry foo.com if everyone hits your name server testing this module. :-)



    tie my %dns, Tie::DNS, {Domain => foo.com};

    while (my ($name, $ip) = each %dns) {
        print "$name = $ip\n";
    }



This obviously requires that your host has zone transfer privileges with a name server hosting that zone. The zone transfer is initiated with the first each, keys or values operation. The tie operation does a SOA query to find the name server for the cited zone.

    Fetching multiple records

Pass the configuration parameter of ’multiple’ to any Perl true value, and all FETCH values from Tie::DNS will be an array reference of records.



    tie my %dns, Tie::DNS, {multiple => true};

    my $ip_ref = $dns{cnn.com};
    foreach (@{$ip_ref}) {
        print "Address: $_\n";
    }



    Fetching records of type besides ’A’

Pass the configuration parameter of ’type’ to one of the Net::DNS supported record types causes all FETCHes to get records of that type.



    tie my %dns, Tie::DNS, {
        multiple => true,
        type => SOA
    };

    my $ip_ref = $dns{cnn.com};
    foreach (@{$ip_ref}) {
        print "primary nameserver: $_\n";
    }



Here are the most popular types supported:



    CNAME - Returns the records canonical name.
    A - Returns the records address field.
    TXT - Returns the descriptive text.
    MX - Returns name of this mail exchange.
    NS - Returns the domain name of the nameserver.
    PTR - Returns the domain name associated with this record.
    SOA - Returns the domain name of the original or
        nameserver for this zone.

    (The descriptions are right out of the Net::DNS POD.)



See Net::DNS documentation for further information about these types and a comprehensive list of all available types.

    Fetching all of the fields associated with a given record type.



    tie my %dns, Tie::DNS, {type => SOA, all_fields => true};

    my $dns_ref = $dns{cnn.com};
    foreach my $field (keys %{$dns_ref}) {
        print "$field = " . ${$dns_ref}{$field} . "\n";
    }



This code fragment will print all of the SOA fields associated with cnn.com.

    Caching

The argument ’cache’ will cause the DNS results to be cached. The default is no caching. The ’cache’ argument is passed through to Tie::Cache. If Tie::Cache cannot be loaded, caching will be disabled. Entries whose DNS TTL has expired will be re-queried automatically.



    tie my %dns, Tie::DNS, {cache => 100};
    print "$dns{cnn.com}\n";
    print "$dns{cnn.com}\n";  ## cached!



    Getting all/different fields associated with a record



    tie my %dns, Tie::DNS, {all_fields => true};
    my $dns_ref = $dns{cnn.com};
    print $dns_ref->{ttl}, "\n";



Passing arguments to Net::DNS::Resolver->new()



    tie my %from_localhost, Tie::DNS, {
        resolver_args => {
            nameservers => [127.0.0.1]
        }
    };
    print "$from_localhost{test.local}\n";



You can pass arbitrary arguments to the Net::DNS::Resolver constructor by setting the resolver_args argument. In the example above, an alternative nameserver is used instead of the default one.

    Changing various arguments to the tie on the fly



    tie my %dns, Tie::DNS, {type => SOA};
    print "$dns{cnn.com}\n";

    tied(%dns)->args({type => A});
    print "$dns{cnn.com}\n";



This code fragment first does an SOA query for cnn.com, and then changes the default mode to A queries, and displays that.

    Simple Dynamic Updates

Assign into the hash, key DNS name, value IP address, to add a record to the zone in the domain argument. For instance:



    tie my %dns, Tie::DNS, {
        domain => realms.lan,
        multiple => true
    };

    $dns{food.realms.lan.} = 131.22.40.1;

    foreach (@{$dns{food}}) {
        print " $_\n";
    }



    Methods

error

Returns the last error, either from Tie::DNS or Net::DNS

get_root_server

Returns the root name server.

do_forward_lookup

Returns the results of a forward lookup.

do_reverse_lookup

Returns the results of a reverse lookup.

args

Change various arguments to the tie on the fly.

TODO

This release supports the basic functionality of Net::DNS. The 1.0 release will support the following:

Different access methods for forward and reverse lookups.

The 2.0 release will strive to support DNS security options.

AUTHOR

Dana M. Diederich <dana@realms.org>

ACKNOWLEDGMENTS

kevin Brintnall <kbrint@rufus.net> for Caching patch Alvar Freude <alvar@a-blast.org> for arguments to resolver patch Greg Myran <gmyran@drchico.net> for fixes for Net::DNS >= 0.69

BUGS

in-addr.arpa zone transfers aren’t yet supported.

Patches, flames, opinions, enhancement ideas are all welcome.

COPYRIGHT Copyright (c) 2009,2013,2015 Dana M. Diederich. All Rights Reserved. This module is free software. It may be used, redistributed and/or modified under the terms of the Perl Artistic License (see http://www.perl.com/perl/misc/Artistic.html)

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perl v5.20.3 TIE::DNS (3) 2015-06-05

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