The usual reason for asking this question is that you want to restart a server but can't because you get a message "can't bind to port". There are adb scripts to close a FIN_WAIT_2 socket, I don't understand why you're having trouble with it. HP also has a program called ndd which can close a connection. But you shouldn't have to do this. Instead you address the real problem which is that the server has a bug that should be fixed.

There are two ways to ignore FIN_WAIT_2 sockets under unix. First, a program like inetd can do the bind at boot-up time and pass off new connections to the server as they arrive. Second, the server can simply set the SO_REUSEADDR option to indicate that it would prefer to ignore them.

You must have a server that does not want to run under inetd and it doesn't set SO_REUSEADDR. Ask whoever wrote the server to fix that. It takes one line of code to set SO_REUSEADDR and then you will have no more problem.