Kill sockets

Sometimes in your System Administrator's life, you have services running that block networking ports. This can result in a program not starting and giving you the error message socket already in use An example is a process listening on port 80. It will make it impossible to start a typical web server because port 80 is the default web server (http or www) port. In order to start a web server, you will have to kill that other process. A socket is the combination of an IP address and a port number.

To kill a process blocking a socket first find the socket you are interested:

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