Find Program Listening on TCP/IP Port in Windows or Linux

In Windows:

To figure out what program is using a particular tcpip port in Windows:

(Useful to examine suspiciously open ports, or to resolve port conflicts)

In WinXP (and higher?),
- netstat -o shows process that owns a connection
- netstat -b shows the executable
- netstat -a shows listening -- this is probably the one you want.
- netstat -a -b show listening + executable name.
E.g. "netstat -p udp -a 100". Then investigate if the output contains line like "UDP YOURCOMPUTERNAME:ms-sql-m". If it does, you might be running MS SQL 2000
In other versions of windows, you can download "TcpView" from systernals.com. It works great, just like the rest of their tools.

For Linux:
netstat is still the program to call. Try the -p option.
With Virtuozzo, I'm not convinced that -p works -- correction, my version of netstat was quite old. Updating the net-tools package with yum "fixed" it, it seems.

ps -Af lists the command line of all programs.

tags: ports, tcpip, program, process, list, win, winxp, linux, locked, port,