Get process that bind a port

[STYMA, ROBERT E (ROBERT)]

> 
> Hello,
> I am playing around with writing a program to bind to socket 
> / port in my 
> machine. Often time, I got the message:
> bind(): Address already in use
> 
> So my question is, how do I find out which process bind to a 
> certain port 
> number ? For example, how do I find out what process use port 
> 2345? Sometimes 
> 'ps ax' does not really show the process that I though bind 
> that port number, 
> although bind() gave the error message. Plus 'ps ax' does not 
> really help 
> unless you know the process name anyway.
> 
> Thanks for any help.
> RDB
> 
The command lsof run as root will tell you a lot of things including
who is bound to a port.
For example:
lsof | grep 2345

Note that on various flavors unix, I have seen the "already in use" message
for a short time after a program exits.  That is, start a program which listens
on a certain port, exit the program, immediately restart the program.  A quick test
says FC4 does not seem to do this.

--
Bob Styma