#!/usr/bin/perl
 use strict;
 use warnings;

 use IO::Socket::INET;

 my $listenSocket = IO::Socket::INET->new(
     'LocalPort' => '12345',
     'Listen'    => SOMAXCONN,
     'Reuse'     => 1,
     'Proto'     => 'tcp',
 ) or die $@;

 my $conSocket = $listenSocket->accept;

 while ( defined $conSocket ) {
     my $rsp = q{};
     $conSocket->sysread( $rsp, 20 ) or die $@;
     print "recv: $rsp\n";

     $conSocket->syswrite( "hello, client!\n" ) or die $@;

 } ## end while ( defined $conSocket)