Scenario

A security audit found several unauthorized applications listening on high ports (range 8000-9000).

Task

Scan the system for listening TCP/UDP ports between 8000 and 9000. Identify the Process IDs (PIDs) bound to these ports and terminate the associated services.

Step 1: Detect and Identify
Use ss (Socket Statistics) to list all listening processes. We use -tulpn to show TCP, UDP, Listening sockets, Processes, and Numeric ports.

sudo ss -tulpn

Observation: You will see output like users:(("python3",pid=1234,fd=3)). Note the PID (1234).

Step 2: Terminate the processes
Send a termination signal to the PIDs identified in the previous step.

kill <PID>

If a process refuses to die, terminate it with

sudo kill -9 <PID>