I would like to know if via Java Code preferably or by Perl whether or not I can find out all the IP and MAC addresses currently connected to my LAN? The LAN would be connected to the Internet via a Linux Box with two Nics - one for the internet and the other for the LAN switch. My custom application would be running on this same box, so if there is a service or other application that I would be able to query in order to get this information and make things easier, let me know.
 If the above is possible, a brief explanation and a supplied example of the key parts of the code would be appreciated.
Note Requirements: Reporting of information to be quick; not eat up a lot of bandwidth; if using SNMP would help, then please incorporate in the solution given.