#! perl -slw
use strict;
use IO::Socket;

socket( SOCKET, PF_INET, SOCK_DGRAM, getprotobyname('udp') ) or die "socket: $!";
bind( SOCKET, sockaddr_in( 54321, inet_aton( 'localhost' ) ) ) or die $!;
my $input;

while( 1 ) {
    my $addr = recv( SOCKET, $input, 1024, 0 ) or die $!;
    my( $port, $ipbin ) = sockaddr_in( $addr );
    printf "Got '%s' from  ip:%s port:%d\n", $input, inet_ntoa($ipbin), $port;
}