Watching packets go by

Low level debug tool #1 is tcpdump to check who said what!
To check any packet between the localhost and target use this:

#tcpdump -X host <target_server_ip> -s 0

-X: decode packet in ascii
-s 0: show the whole packet.

Scrolling too fast? Pipe it into | more and scroll at your leisure or pipe it into grep and catch only the important stuff!