how to identify the systems which are connected in java

[sreelakshmi kolla]

Hi All,

I am working on implementing the intenal LAN messenger.here i want ti identify the systems which are connected in LAN and get their names.
can any one tell how to do this?

Thanks&Regards,
Sreelakshmi.

[Joe Ess]

There is no way to query a TCP/IP network to find who is connected short of pinging every available address for a well-known service (ping, echo, time). This practice is frowned upon by network engineers and is usually considered an attack. The conventional way a messenger service compiles a list of clients is by having clients register with a central server.