Others have pointed out vairous structures and file processing mechanics.

There are two modules that will help you validate and manipulate IP addresses:

• Regex::Common will help validate/extract IP addresses from text
• NetAddr::IP will help deal with IP address ranges, and easily discover if a particular address is within a specified range

  my $ip = new NetAddr::IP 'loopback';

  print "The address is ", $ip->addr, " with mask ", $ip->mask, "\n" ;

  if ($ip->within(new NetAddr::IP "127.0.0.0", "255.0.0.0")) {
      print "Is a loopback address\n";
  }

# Or - more likely you want to use this ..
$me->contains($other) ...
[download]