The SSH protocol provides the following safeguards:
After an initial connection, the client can verify that it is connecting to the same server it had connected to previously.
The client transmits its authentication information to the server using strong, 128-bit encryption.
All data sent and received during a session is transferred using 128-bit encryption, making intercepted transmissions extremely difficult to decrypt and read.
The client can forward X11[6] applications from the server. This technique, called X11 forwarding, provides a secure means to use graphical applications over a network.
Because the SSH protocol encrypts everything it sends and receives, it can be used to secure otherwise insecure protocols. Using a technique called port forwarding, an SSH server can become a conduit to securing otherwise insecure protocols, like POP, and increasing overall system and data security.
Red Hat Enterprise Linux includes the general OpenSSH package (openssh) as well as the OpenSSH server (openssh-server) and client (openssh-clients) packages. Refer to the chapter titled OpenSSH in the Red Hat Enterprise Linux System Administration Guide for instructions on installing and deploying OpenSSH. Note, the OpenSSH packages require the OpenSSL package (openssl) which installs several important cryptographic libraries, enabling OpenSSH to provide encrypted communications.
[6] X11 refers to the X11R6.7 windowing display system, traditionally referred to as the X Window System or X. Red Hat Enterprise Linux includes XFree86, an open source X Window System.