How to find what ports are open in Linux
To find out what ports are open / listening on your Linux, use the following netstat commands in the terminal. Note that you need to login as root (superuser) to use them.
netstat –listen netstat -tulpn
The first would let you see what ports are listening and the second will list the processes. To have a total reference of all the netstat commands, check out the man page for netstat.
Assume that TCP port 3306 was opened by mysqld process having PID # 1138.
You can verify this using /proc, enter:
ls -l /proc/1138/exe
You can use grep command to filter out information:
netstat -tulpn | grep :80
You can alse use the fuser commands.
To find out the processes PID that opened tcp port 7000, enter:
To find out process name associated with PID # 3813, enter:
ls -l /proc/3813/exe
To kill a process use the following command
fuser -k 8080/tcp