Install fwknop-client by entering the following commands in the terminal:
sudo apt update sudo apt install fwknop-client
Description:
FireWall KNock OPerator client side - C version
The FireWall KNock OPerator implements an authorization scheme called Single Packet Authorization (SPA), based on Netfilter and libpcap. . Its main application is to protect services such as OpenSSH with an additional layer of security in order to make the exploitation of vulnerabilities (both 0-day and unpatched code) much more difficult. . This is the client program responsible for accepting password input from the user, constructing SPA packets that conform to the fwknop packet format, and encrypting packet data.
Homepage: http://www.cipherdyne.com/fwknop/
Version: 2.6.9-2
Section: universe/admin