Interesting. I cannot replicate this on my system.

I added code for handling the case when the IO::Socket fails, it will now give a message. I don't see (yet) any way now to not get output for each server:port.

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1135109
# http://perlmonks.org/?node_id=11103970

use strict;
use warnings;
use IO::Socket;
use IO::Select;
use Time::HiRes qw( time );

my @ips = map "192.168.1.$_", 1..20; # your IPs here
push @ips, 'doesnotexist.com', 'doesnotexist'; # test for non existent
my $port = 22; # your port here
my $max = 1000; # somewhat smaller than max "open files"
my $timeout = 1;

my %handles;
my $sel = IO::Select->new;

while( @ips or $sel->count )
  {
  if( @ips and $sel->count < $max )
    {
    my $ip = shift @ips;
    if( my $fh = IO::Socket::INET->new(PeerHost => $ip, PeerPort => $p
+ort,
      Proto => 'tcp', Blocking => 0))
      {
      $handles{$fh} = ["$ip:$port", $fh, time]; 
      $sel->add($fh);
      }
    else
      {
      print "not exist  $ip:$port\n";
      }
    }
  elsif( @ips ? $sel->count >= $max : $sel->count )
    {
    my @connects;
    for my $fh ( @connects = $sel->can_write($timeout) )
      {
      print $fh->connected ? '   ' : 'not', " alive  $handles{$fh}[0]\
+n";
      $sel->remove($fh);
      delete $handles{$fh};
      }
    if( not @connects )
      {
      my $time = time - $timeout;
      for my $key ( keys %handles )
        {
        if( $handles{$key}[2] < $time )
          {
          print "not alive  $handles{$key}[0]\n";
          $sel->remove( $handles{$key}[1] );
          delete $handles{$key};
          }
        }
      }
    }
  }
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