I wrote a program for finding all of the Lantronix devices on the network:
jjeffers@solar:~/lantronix$ findLantronix # The following Lantronix devices are on the local network: 192.168.10.232 00:20:4A:A8:49:F3 jjeffers@solar:~/lantronix$
Below is the code, if you want to play with it. Basically the Lantronix will send a reply if it gets a special UDP packet on port 30718. Then you can see what IP replied, firmware version, and MAC address.
-James Jefferson Jarvis APRS World, LLC +1-507-454-2727 www.aprsworld.com