Messaging over TCP

hi all!

i want to know how to get it on when i want to watch what's going on between a server which is located anywhere on the internet and my computer that has got a client application that connects to the server and talks to it.

let's say all msgs are sent in plaintext... how can i watch the traffic between them?

any suggestions?

p.s. i've got a sniffer program for this but this is not what i want... i want a program that reads the msgs and handles events if specified words are sent between the client app and the server.