In my endless search for the perfect regex, I have encountered this problem over and over again. 
### Haxor ###
#!/usr/bin/perl -w

use strict;
use warnings;

my $flag = 0;
my $hacklist = "hack.txt";
my $date = 'Date:    ';
my $octet = '(\d{1,3}\.){3}\d{1,3}';

open HACK, $hacklist or die "Can't Open $hacklist";
my @hack=<HACK>;
close(HACK);

foreach (@hack) {
    
    if (s/$date//){
        print;
        $flag = 0;
    }    
    if (/$octet/ and !$flag){
        print STDOUT $_;
        print "\n";
        $flag = 1;
        }
    }

[download]
Simple, parse the dates and octets from the hacklist. Currently I get this: 
Thursday, December 13, 2001  07:53 AM
Subject:        FW: Please disconnect 208.202.183.42 thanks.

Monday, December 17, 2001  08:56 AM
Subject:        FW: Please disconnect 213.14.199.133 thanks.

[download]
But how do I print only the octet? Everything else on that line is unecessary. Is there a way to print only the matched pattern, disregarding everything else on the line? Ideal results would be: 
Thursday, December 13, 2001  07:53 AM
208.202.183.42

Monday, December 17, 2001  08:56 AM
213.14.199.133

[download]
Hopefully I will get 'Mastering Regular Expressions' for Christmas. Happy Holidays!

In reply to Octet Regex by amearse

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