This directory contains some test code for playing around with multicast UDP messages.
Note: default firewall rules on several kinds of linux system will block ingress multicast
traffic. Although this code will compile and run on any linux system, it may not work
as you expect due to the firewall settings!

Compile in the usual way by running make

To use the tool and play with it:
Run one instance of test_udp on each system you want to test, ensuring firewalls are
OK for multicast. Each instance starts one sender and one receiver. The sender will
launch one packet every two seconds. The receiver should log packets as they arrive
and you should see the packets from different systems interleaved.

Multicast packets from the clock will be displayed as well as test packets from the
tool itself.

If you cannot see any packets coming in, you can install tcpdump and monitor at the
kernel level.

sudo apt-get install tcpdump

The multicast IP address used by the test code and by the alarm-clock software is
225.45.21.183. You can run the tcpdump programme (after it is installed) as follows:

sudo tcpdump host 225.45.21.183
