Another way which you may want to go is to make use of the low-level libpcap packet capturing library through the combined usage of theNet::Pcap and NetPacket modules. This approach, while more involved, offers greater control over the router communication.

For example, the following snippet of code can be used to capture UDP packets from the local network:

use Net::PcapUtils;
use NetPacket::IP;
use NetPacket::UDP;
use NetPacket::Ethernet qw/:types/;
use strict;

Net::PcapUtils::loop(
    sub {
        my ($arg, $header, $packet) = @_;
        my $ethernet = NetPacket::Ethernet->decode($packet);
        if ($ethernet->{'type'} == ETH_TYPE_IP) {
            my $ip = NetPacket::IP->decode($ethernet->{'data'}, $ether
+net);
            my $udp = NetPacket::UDP->decode($ip->{'data'});

            .
            .

            print
                $ip->{'src_ip'}, ":", $udp->{'src_port'}, " -> ",
                $ip->{'dest_ip'}, ":", $udp->{'dest_port'}, "\n";
        }
    },
    'DEV'       =>  'eth0',
#    'FILTER'    =>  'udp dst host 192.168.1.1'
);
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The commented line in the above code snippet is an example filter which can be passed the packet-capturing library to minimise unwanted 'overhead' packets also captured.

With regard to the initial UDP broadcast over the network, you will need to set the SO_BROADCAST option on the socket in order to request permission for the communication given the priviledged nature of this type of communication. For example:

use IO::Socket;
use strict;

my $sock = new IO::Socket::INET(
    'PeerAddr'  =>  '55.255.255.255'
    'PeerPort'  =>  '9',
    'Proto'     =>  'udp'
);
$sock->sockopt(SO_BROADCAST, 1);
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Alternatively, depending upon your data requirements, the NetPacket group of modules referenced earlier can also be used to manually construct packets for transmission.