With UDP sockets, the server receves packets, and the client sends them

If you can get hold of a copy, then you should take a look at the examples in Perl Cookbook (O'Reilly). Otherwise, take a look at IO::Socket::INET in CPAN.

Here is a quick example:

Client:

my $sendSock = IO::Socket::INET->new( 'Proto'    => 'udp',
                                          'PeerPort' => $udp_port,
                                          'PeerAddr' => $hostname,
    ) or die("Error creating socket $!");

$sendSock->send($data) or die("Socket send error $!");
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Server:

my $listenSock = IO::Socket::INET->new('LocalPort'=>$udp_port, 'Proto'
+=>'udp');
my $readBuff;
$listenSock->recv( $readBuff, $MAX_BYTES );
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Note that the server above will block until some data is received.