#!/usr/bin/env perl

use strict;
use warnings;

use Fcntl qw ( :flock );
use IO::Socket;

my $in_file2 = 'rang.txt';
open( my $input,  "<", $in_file2 )  or die $!;
open( my $output, ">", "port.txt" ) or die $!;

my $manager = Parallel::ForkManager->new(20);
foreach my $ip (<$input>) {
    $manager->start and next;

    chomp($ip);
    my $host = IO::Socket::INET->new(
        PeerAddr => $ip,
        PeerPort => 80,
        proto    => 'tcp',
        Timeout  => 1
    );
    if ( defined $host ) {
        flock( $output, LOCK_EX );    #exclusive or write lock
        print {$output} $ip, "\n";
        flock( $output, LOCK_UN );    #unlock
    }
    $manager->finish;
}
$manager->wait_all_children;
close($output);
close($input);