How To Install knock on CentOS 8

knock is A port-knocking server/client

Introduction

In this tutorial we learn how to install knock on CentOS 8.

What is knock

This is a port-knocking server/client. Port-knocking is a method where a server can sniff one of its interfaces for a special “knock” sequence of port-hits. When detected, it will run a specified event bound to that port knock sequence. These port-hits need not be on open ports, since we use libpcap to sniff the raw interface traffic. This package contains the knock client.

We can use yum or dnf to install knock on CentOS 8. In this tutorial we discuss both methods but you only need to choose one of method to install knock.

Install knock on CentOS 8 Using dnf

Update yum database with dnf using the following command.

sudo dnf makecache --refresh

The output should look something like this:

CentOS Linux 8 - AppStream                                       43 kB/s | 4.3 kB     00:00    
CentOS Linux 8 - BaseOS                                          65 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - ContinuousRelease                               43 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - Extras                                          23 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - FastTrack                                       40 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - HighAvailability                                36 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - Plus                                            24 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - PowerTools                                      50 kB/s | 4.3 kB     00:00    
Extra Packages for Enterprise Linux Modular 8 - x86_64           13 kB/s | 9.2 kB     00:00    
Extra Packages for Enterprise Linux 8 - x86_64                   24 kB/s | 8.5 kB     00:00    
Metadata cache created.

After updating yum database, We can install knock using dnf by running the following command:

sudo dnf -y install knock

Install knock on CentOS 8 Using yum

Update yum database with yum using the following command.

sudo yum makecache --refresh

The output should look something like this:

CentOS Linux 8 - AppStream                                       43 kB/s | 4.3 kB     00:00    
CentOS Linux 8 - BaseOS                                          65 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - ContinuousRelease                               43 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - Extras                                          23 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - FastTrack                                       40 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - HighAvailability                                36 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - Plus                                            24 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - PowerTools                                      50 kB/s | 4.3 kB     00:00    
Extra Packages for Enterprise Linux Modular 8 - x86_64           13 kB/s | 9.2 kB     00:00    
Extra Packages for Enterprise Linux 8 - x86_64                   24 kB/s | 8.5 kB     00:00    
Metadata cache created.

After updating yum database, We can install knock using yum by running the following command:

sudo yum -y install knock

How To Uninstall knock on CentOS 8

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

sudo dnf remove knock

knock Package Contents on CentOS 8

/usr/bin/knock
/usr/lib/.build-id
/usr/lib/.build-id/5d
/usr/lib/.build-id/5d/378d4b8d74ed973cb6f455bb449ead8b8ee896
/usr/share/doc/knock
/usr/share/doc/knock/COPYING
/usr/share/doc/knock/ChangeLog
/usr/share/doc/knock/README.md
/usr/share/doc/knock/TODO
/usr/share/licenses/knock
/usr/share/licenses/knock/COPYING
/usr/share/man/man1/knock.1.gz

References

Summary

In this tutorial we learn how to install knock on CentOS 8 using yum and dnf.