Killing Open Ports in Linux

Posted on 27 Jan, 2020

I had this weird error while running Django Development Server.

System check identified no issues (0 silenced).
January 27, 2020 - 16:42:39
Django version 2.2.9, using settings 'codeclassroom.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
Error: That port is already in use.

Solution

1. Run netstat -ntlp to see available open ports.

(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.1:42405         0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:5940          0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:8000          0.0.0.0:*               LISTEN      12054/python3       
tcp6       0      0 ::1:631                 :::*                    LISTEN      -  

Here is a man netstat for what it does

netstat - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships

You see the python3 one? Kill 😈 this process

1. Run kill -9 12054 Kill is used for Removing a background process or job, -9 specifies SIGKILL (Forced termination) where 12054 is the PID

2. Run the development server again.