Network Tools

I’ve not spent a lot of time with sockets until a recent project and it’s been a definitely learning experience.  There is nothing like the School of Lessons Learned the Hard Way to truly learn something.

I ran across a tool today that is now definitely in my standard toolbox.  If you ever receive a Port In Use error when dealing with sockets, on Windows at least, you can find out what ports are in use by what applications by using TCPView which is a free download from  This nifty utility lets you easily see which processes have what ports open, TCP or UDP, how much data has been transferred, etc.  It even resolves the addresses of any clients that are connecting to that port.  Very handy and extremely useful.

Is there such a tool available for Mac OS X?

When dealing with networking, what tools do you find invaluable?

2 thoughts on “Network Tools

  1. The netstat command (with switches) would probably do the same on Mac OS X. On Linux it would be “netstat -an” at least.

  2. “netstat -ano” in Windows also would display the whole list, and the Process ID of the program using the port. This is a very nice utility to have, real time updates and it looks up the PID and gives you the Application Name. The only thing that would improve upon that would be if it could give you the underlying DLL which Service Host (svchost.exe) was running on that port. “tasklist /svc” will show all the DLLs or services running on each Service Host, but they share the same PID.

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