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!