nagios_check_port.pl

#!/usr/bin/env perl

use strict;
use warnings;
use IO::Socket;
use threads;
use Thread::Queue;

my $count : shared;
my $hostcnt : shared;
my $thrnum :  shared = 50; # change to adjust performance
my @host_list : shared;

sub scan {
    my ($data) = @_;
    my ($host, $port) = split /\s+/, $data;
    #print "$host : $port ";
    my $sock = new IO::Socket::INET (PeerAddr => $host, PeerPort => $port, Timeout => 1);
    if ($sock) {
        #print "OK\n";
        close $sock;
    } else {
        #print "CRITICAL\n";
        push @host_list, "$host:$port";
    }
}


#print " Building queue... \n";
my $q = Thread::Queue->new();
open my $HOSTS, 'port_list.txt' or die $!;
while (<$HOSTS>) {
    next if /^#/ || /^\s+$/;
    chomp $_;
    $q->enqueue($_);
    $hostcnt++;
}
close $HOSTS;

#print "Added $hostcnt hosts\n";
#print "$thrnum worker thread(s) will be spawned\n";
#print "Scan initiated for $hostcnt hosts\n";

while (1) {
    my @threads = threads->list;
    if ($q->pending > 0) {
        if  ($#threads <= $thrnum + 1) {
            threads->new(\&scan, $q->dequeue);
            $count++;
        } else {
            foreach my $running (@threads) {
                $running->join();
            }
        }
        #printf " %s hosts scanned\n", $count;
    } else {
        if ($#threads > 0) {
            foreach my $running (@threads) {
                $running->join();
            }
        }
        last;
    }
}

#print "\nThe following ports closed\n";
if ( @host_list ) {
    print "CRITICAL - ";
    foreach ( @host_list ) {
        print "$_ ";
    }
    print "closed\n";
    exit 2; # Critical
} else {
    print "OK - $count ports opened\n";
    exit 0; # OK
}
print "UNKNOWN\n";
exit 1;