NAME

Net::DNS::QueryID - random Query ID numbers

SYNOPSIS

Functions to manage a cache of random Query ID's for DNS packets.

The purpose of this module is to provide and unpredictable source of 16 bit DNS Query ID numbers to help defeat cache poisoning using DNS Spoofing or "Man in the Middle" attacks as describe in the Wikipedia article and its references:

        http://en.wikipedia.org/wiki/DNS_cache_poisoning

  use Net::DNS::QueryID qw(
        id_get
        id_clr
        id_busy
  );

  $queryID = id_get();
  $result  = id_clr($queryID);
  $result  = id_busy($queryID);

• $queryID = id_get();

    input:        none
    returns:      16 bit integer from 1 - 65535
                  that is not currently in the cache.
                  false (0) if all 65535 ID's are in use

• $result = id_clr($queryID);

    input:        Query ID to clear
    returns:      true (the Query ID) on success
                  false if the Query ID is not in use
                  false if the Query ID is out of range
                  i.e. not 1 -1 65535

• $result = id_busy($queryID);

    input:        Query ID
    returns:      true if Query ID is in the cache
                  false if Query ID is not in the cache
                  false if Query ID is out of range
                  i.e. not 1 -165535

EXPORTS_OK

        id_get
        id_clr
        id_busy

AUTHOR

Michael Robinton <michael@bizsystems.com>

COPYRIGHT 2012-2014

Michael Robinton <michael@bizsystems.com>

All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of either:

  a) the GNU General Public License as published by the Free
  Software Foundation; either version 2, or (at your option) any
  later version, or

  b) the "Artistic License" which comes with this distribution.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either the GNU General Public License or the Artistic License for more details.

You should have received a copy of the Artistic License with this distribution, in the file named "Artistic". If not, I'll be glad to provide one.

You should also have received a copy of the GNU General Public License along with this program in the file named "Copying". If not, write to the

        Free Software Foundation, Inc.
        59 Temple Place, Suite 330
        Boston, MA  02111-1307, USA

or visit their web page on the internet at:

        http://www.gnu.org/copyleft/gpl.html.