#!/usr/bin/perl 
use strict;
use warnings;

while (<DATA>) {
    if (/:.+\@.+\s([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})/) {
        print $1;
    }
}

__DATA__
random.ircserv.net 378 ircop Blueink :is connecting from *@78.273.80.23 78.273.80.23