How To Install knockd on Ubuntu 22.04

In this tutorial we learn how to install knockd on Ubuntu 22.04. knockd is small port-knock daemon

Introduction

In this tutorial we learn how to install knockd on Ubuntu 22.04.

What is knockd

knockd is:

A port-knock server that listens to all traffic on a given network interface (only Ethernet and PPP are currently supported), looking for a special “knock” sequences of port-hits. A remote system makes these port-hits by sending a TCP (or UDP) packet to a port on the server. When the server detects a specific sequence of port-hits, it runs a command defined in its configuration file. This can be used to open up holes in a firewall for quick access.

There are three methods to install knockd on Ubuntu 22.04. We can use apt-get, apt and aptitude. In the following sections we will describe each method. You can choose one of them.

Install knockd Using apt-get

Update apt database with apt-get using the following command.

sudo apt-get update

After updating apt database, We can install knockd using apt-get by running the following command:

sudo apt-get -y install knockd

Install knockd Using apt

Update apt database with apt using the following command.

sudo apt update

After updating apt database, We can install knockd using apt by running the following command:

sudo apt -y install knockd

Install knockd Using aptitude

If you want to follow this method, you might need to install aptitude first since aptitude is usually not installed by default on Ubuntu. Update apt database with aptitude using the following command.

sudo aptitude update

After updating apt database, We can install knockd using aptitude by running the following command:

sudo aptitude -y install knockd

How To Uninstall knockd on Ubuntu 22.04

To uninstall only the knockd package we can use the following command:

sudo apt-get remove knockd

Uninstall knockd And Its Dependencies

To uninstall knockd and its dependencies that are no longer needed by Ubuntu 22.04, we can use the command below:

sudo apt-get -y autoremove knockd

Remove knockd Configurations and Data

To remove knockd configuration and data from Ubuntu 22.04 we can use the following command:

sudo apt-get -y purge knockd

Remove knockd configuration, data, and all of its dependencies

We can use the following command to remove knockd configurations, data and all of its dependencies, we can use the following command:

sudo apt-get -y autoremove --purge knockd

References

Summary

In this tutorial we learn how to install knockd package on Ubuntu 22.04 using different package management tools: apt, apt-get and aptitude.