Install knocker by entering the following commands in the terminal:
sudo apt update sudo apt install knocker
Description:
Simple and easy to use TCP security port scanner
Knocker is a new, simple, and easy to use TCP security port scanner written in C, using threads. It is able to analyze hosts and the network services which are running on them.
Homepage: http://knocker.sourceforge.net/
Version: 0.7.1-5
Section: universe/net