knock_helper_ipt.sh command not found

Introduction

When you run more command in linux terminal / console, you get the following error message

knock_helper_ipt.sh: command not found

or when using sudo you get the following error message

sudo: knock_helper_ipt.sh: command not found

Solutions to knock_helper_ipt.sh: command not found

How To Fix knock_helper_ipt.sh: command not found in Ubuntu / Debian / Kali Linux / Raspbian

In Ubuntu knock_helper_ipt.sh is provided by knockd package.

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.

To fix this problem, we can install more using the command below.

sudo apt-get -y install knockd

This command might take some time to finish depending on your machine internet connection.

You can also use apt command to install knockd.

sudo apt -y install knockd

Or if you have aptitude installed you can use the following command.

sudo aptitude install knockd

Summary

In this tutorial we learn how to fix knock_helper_ipt.sh command not found error in Ubuntu / Debian / Kali Linux or Raspbian distribution.