#! /usr/bin/perl -w 

use strict;
use Socket;

use constant SIMPLE_UDP_PORT => 4001;
use constant MAX_RECV_LEN => 1500;
use constant LOCAL_INETNAME => 'localhost';

my $trans_serv = getprotobyname('udp');

my $local_host = pack "C4", split('\.', "127.0.0.1");

my $local_port = shift || SIMPLE_UDP_PORT;
my $local_addr = sockaddr_in($local_port, INADDR_ANY);

socket(UDP_SOCK, PF_INET, SOCK_DGRAM, $trans_serv);

bind(UDP_SOCK, $local_addr);

my $data;

while(1)
{
	my $from_who = recv(UDP_SOCK, $data, MAX_RECV_LEN, 0);
	
	if ($from_who)
	{
		my($the_port, $the_ip) = sockaddr_in($from_who);
		warn 'Received from ', inet_ntoa($the_ip), ": $data\n";
	}
	else
	{
		warn "Problem with recv: $!\n";
	}
}