Thank you very much

I followed your advice, but somehow the send doesn't reach the server (on the same host). The network is fine, and Ikegamis script works perfect (except that it is not broadcasting).

server.pl:

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

use Socket qw(:all);

$|++; # no suffering from buffering

my $udp_port = 9999;

socket( UDPSOCK, PF_INET, SOCK_DGRAM, getprotobyname('udp') ) or die "
+socket: $!";

select( ( select(UDPSOCK), $|=1 )[0] ); # no suffering from buffering

setsockopt( UDPSOCK, SOL_SOCKET, SO_REUSEADDR, 1 )
    or die "setsockopt SO_REUSEADDR: $!";
#setsockopt( UDPSOCK, SOL_SOCKET, SO_BROADCAST, 1 )
#    or die "setsockopt SO_BROADCAST: $!";

# my $broadcastAddr = sockaddr_in( $udp_port, INADDR_BROADCAST );
my $broadcastAddr = sockaddr_in( $udp_port, INADDR_ANY );
bind( UDPSOCK, $broadcastAddr ) or die "bind failed: $!\n";

my $input;
while( my $addr = recv( UDPSOCK, $input, 4096, 0 ) ) {
    print "$addr => $input\n";
}
[download]

Client.pl

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

use Socket qw(:all);
use POSIX ":sys_wait_h";

socket( SOCKET, PF_INET, SOCK_DGRAM, getprotobyname("udp") )
    or die "Error: can't create an udp socket: $!\n";

select( ( select(SOCKET), $|=1 )[0] ); # no suffering from buffering

my $broadcastAddr = sockaddr_in( 9999, INADDR_BROADCAST );
setsockopt( SOCKET, SOL_SOCKET, SO_BROADCAST, 1 );

send( SOCKET, "a" x 4096, 0,  $broadcastAddr )
    or die "Error at sendding: $!\n";

close SOCKET;
[download]

Does anybody know what I'm doing wrong?

My friend intends to use broadcasts to announce a new server going online to a central service. He won't misuse it. I am interested in this topic, because I know a little bit about TCP/IP, but have hardly any knowledge about UDP and broadcasts.