how can we sniff traffic between two ports of same machine?

Question

I am testing a thick client which is connected to a database, need to sniff traffic b/w tcp port on same machine

Answer 1

You can try some tools like WireShark.

Answer 2

Assuming you're on Windows:

I'd split the client and server across two machines, either two real ones, or a VM with something VMWare. Then I'd use Wireshark.

Answer 3

WireShark (formerly Etereal) will work perfectly, if you're not familair with it, it can be a little tricky on OSX, Windows it's no problem and Linux can be a headache. You can download it here http://www.wireshark.org/, and read a short-primer here - http://www.ipprimer.com/packets.cfm

Essentially there's a capture phase, and then you can work with the data – for your purposes you can live-capture and filter the output to the packets on the port/destination you care about, I've used it many-a-time to debug dodgy home networking, or problems at the office.

Beware if using MySQL and localhost for example, this is a key-word for MySQL and it will infact use the socket instead.. which makes things a matter more complicated, you can circumvent this problem by always making sure to use 127.0.0.1 if working with MySQL. (Perhaps other software uses this convention?)