Identify a process who is listening in a port

Sometimes you need to identify a process than is associated to a TCP port.

You can use ss instead netstat command to identify them.

For instance, if you want to identify what is the process who is listen on TCP port 80, use the following command:

# ss -ltnp | grep -w ':80'

LISTEN   0         128                 0.0.0.0:80               0.0.0.0:*        users:(("nginx",pid=24503,fd=13),("nginx",pid=24502,fd=13),("nginx",pid=24499,fd=13))

Where:

• l – tells netstat to only show listening sockets.
• t – tells it to display tcp connections.
• n – instructs it show numerical addresses.
• p – enables showing of the process ID and the process name.

Then, with the process number (i.e. 24499) you can get the process detail with:

# ls -l /proc/24499/exe
lrwxrwxrwx. 1 root root 0 Jun  3 08:37 /proc/24499/exe -> /opt/opscode/embedded/sbin/nginx