SSH: The Secure Shell (The Definitive Guide)
Barrett, Silverman, & Byrnes / O’Reilly

SSH Frequently Asked Questions

What's the difference between SSH and SSL/TLS?

SSL stands for "Secure Sockets Layer;" TLS, for "Transport Layer Security." SSL was developed by Netscape for use in securing HTTP. That is still its principal use, although there is nothing specific to HTTP about SSL. When a browser accesses a URL which begins with "https", it speaks HTTP over an SSL connection. TLS is the name of the IETF protocol standard that grew out of SSL 3.0, and is documented by RFC 2246. We will use the term "TLS."

TLS has goals and features similar to those of the SSH Transport and User Authentication protocols. It provides a single, full-duplex byte stream to clients, with cryptographically assured privacy and integrity, and optional authentication. It differs from SSH in the following principal ways: