Freeing up a TCP/IP port?

netstat -tulnap shows me what ports are in use. How to free up a port in Linux?

As the others have said, you'll have to kill all processes that are listening on that port. The easiest way to do that would be to use the fuser(1) command. For example, to see all of the processes listening for HTTP requests on port 80 (run as root or use sudo):

# fuser 80/tcp

If you want to kill them, then just add the -k option.

To kill a specific port in Linux use the below command

sudo fuser -k Port_Number/tcp

replace Port_Number with your occupied port.

In terminal type :

netstat -anp|grep "port_number"

It will show the port details. Go to last column. It will be in this format . For example :- PID/java

then execute :

kill -9 PID. Worked on Centos5

For MAC:

lsof -n -i :'port-number' | grep LISTEN

Sample Response :

java   4744 (PID)  test  364u  IP0 asdasdasda   0t0  TCP *:port-number (LISTEN)

and then execute :

kill -9 PID 

Worked on Macbook

You can use tcpkill (part of the dsniff package) to kill the connection that's on the port you need:

sudo tcpkill -9 port PORT_NUMBER

To check all ports:

netstat -lnp

To close an open port:

fuser -k port_no/tcp

Example:

fuser -k 8080/tcp

In both cases you can use the sudo command if needed.