It keeps coming up from time to time again, so I thought I post it here and see if I get a hit: I’m having some slight problems with one of my custom SMTP clients and I need to debug the TCP/IP connection for communication to see what’s happening and compare to say what Outlook is doing.

I need a network monitoring tool basically. Something like what Microsoft’s Network Monitor does, but in a more usable format. Everytime I fire up Network Manager I forget just how I need to run it and worse how to filter the data to get only what I want. What I want to see in this case is the communication on Port 25. Specify the port and let it record the high level traffic that goes through it...

Does anybody know of a tool that can monitor on the TCP/IP port level and filter by that? Something like Fiddler but for an arbitrary port that just listens to the specific port and captures the conversation? It should be easy to use and a preferably in the consumer tool price range (or free <g>) rather than in the corporate network price range, if you know what I mean…

Searching for this sort of thing is a bit difficult as you get loads of up time monitoring tools...

Any ideas?