Security Strategies in Linux Platforms and Applications, 3rd Edition

Basic Principles of Encryption on Networks

You’ve just read about one method of encrypted communication, using SSH. Other methods are available. One that is commonly used is Internet Protocol Security (IPSec). IPSec is a set of extensions to IP that were developed as part of IPv6 but can be implemented along with IPv4 to allow encryption between two hosts. It works at both ends of a connection, tunneling communications through protocols 50 and 51. In tunneling mode, it is a form of virtual private networking.

Another method is based on the Transport Layer Security (TLS) protocol. TLS has long superseded the Secure Sockets Layer (SSL), but some people continue to refer to it as SSL, in spite of the fact that TLS has been the encryption protocol ...