See: Testing for port connectivity. JSchmitz shows you how to get the status of a single port, and McDarren shows how to handle multiple hosts. Here's an example:

#!/usr/bin/perl 

use strict;
use warnings;
use IO::Socket::PortState qw(check_ports);

my $proto   = 'tcp';
my $port    = '80';
my $address = '127.0.0.1'; 

my($section, $ping_timeout, %porthash);
$porthash{$proto}{$port}{'name'} = $section;
check_ports($address, $ping_timeout, \%porthash);

my $open = $porthash{$proto}{$port}{'open'};
if ($open) {
    print "alive\n";
}
else {
    print "dead\n";
}
[download]