how to chat in the given NETWORK

Hello,
I am working on interaction in the LAN. I am able to chat with multiple users in a given FEDORA system using write,wall. But they are limited to a single IP ADDRESS.

But now I want to conduct a chatting program where multiple users can chat who are at different IP addresses. Can you please tell me the command I can use to perform this. If possible can you please give me an example how to use them.
I tried using "ytalk".But it says no domain.I am unable to connect it.

1)can u please send me the link where I can know how to use "ytalk".

2)can u please give me any other command other than ytalk for multiple ip address