From LQWiki

You can kill a socket with netstat.

First, find the socket you are interested in killing:

netstat -avp

"a" for "all," "v" for "verbose," and then "p" for "process" (show process #). For example, you could find a line

tcp   0   0 *:www   *:*   LISTEN   6670/apache2

This means that the process with the id 6670 listens on the www-port.

cat /etc/services | grep 

tells you that the www-port is port 80:

www   80/tcp   http   # WorldWideWeb HTTP

Then kill the respective process:

kill -9 6670