Just to show you why I recommended an Async package, here's your problem done using my own Async::Tiny. It should be similarly short in any of the other Async packages.

#!/usr/bin/perl

use strict;
use warnings;
use Async::Tiny;
use Path::Tiny;

use constant PORT1 => 5000;
my $connID;

my $t = Async::Tiny->new;
$t->addListenCallback( PORT1, sub
  {
  my $sock = shift;
  $t->addReadCallback($sock, \&process_message, $sock->peerhost, ++$co
+nnID);
  $t->changeReadMode($sock, 'full');
  });
$t->eventloop;

sub process_message
  {
  my ($data, $peerhost, $id) = @_;
  my $filename = "rcv_${id}_$peerhost.txt";
  path($filename)->spew_raw($data);
  print "[save process_message] wrote $filename\n";
  }
[download]

See - nice, simple, clean, short :)

Where Async::Tiny is

> my own Async::Tiny

Any plans to CPANify it?

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

I've been thinking about it, but it really needs a humongous test suite ( much more than the 50 or so test programs I have now ) and it needs automation of client/server test cases which now require visual validation, and "more silly excuses"x100 .