Are you trying for this. see the Example.

use strict;
use warnings;

while(1)
{
        my $data=<STDIN>;
        if($data =~ /ipw\.[ar][a-z][a-z]*/)
        {
                print "Match\t\t$data \n";
        }
        else
        {
                print "Not Match $data\n";
        }
}
[download]

We already answered for this question in "dont consider if (......)". First you learn regular expression.
Refer the following Links.

http://networking.ringofsaturn.com/Unix/regex.php#Grouping
http://www.troubleshooters.com/codecorn/littperl/perlreg.htm
--sugumar--