#!/usr/bin/perl

# server.pl

use strict;
use warnings;

use IO::Socket::INET;

my $sock = IO::Socket::INET->new(
   Proto     => 'tcp',
   LocalPort => 5003,
   Listen    => 1,
) or die;

my $client = $sock->accept()
   or die;

for (;;) {
   my $x = sprintf( '%04d', rand(1000) );
   print( "$x\n" );
   print $client ( $x ) or last;
   sleep(1);
}