Error : Adderss is already in use.

Hims · 02-03-2009, 12:18 AM

hi, i am new in the LINUX platform,i am trying to communicate between the server and a client.First time the program executed and i got the output but from second time an error message is coming that Address is already in use.
if((rc = setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))) < 0);
this function is returning -1,
if the port is in use, then how to resue the port.
i am totally in dark please help me.

jimvin · 02-03-2009, 03:04 AM

Hi,
If it worked the first time and not the second then I suggest that the first instance of the program is still running. This would account for the port still being in use. Check the process list using ps to see if there is a copy of the program running.

You can use netstat to show you what is listening on each port:

netstat -nap

Regards,
Jim

Quigi · 02-04-2009, 01:06 PM

If you know the port number (e.g., 4711) "lsof -i :4711" can be very helpful. I think "lsof" is "list open files" -- it can answer that, too. Run as root if you don't own the process that's listening on :4711, otherwise lsof won't tell you.

Probably you get the same information as from netstat, but I find lsof easier to use.
/Quigi