The OpenSSH and OpenSSL projects are in constant development, and the most up-to-date information for them is available from their websites. The man pages for OpenSSH and OpenSSL tools are also good sources of detailed information.
The ssh, scp, sftp, sshd, and ssh-keygen man pages — These man pages include information on how to use these commands as well as all the parameters that can be used with them.
http://www.openssh.com/ — The OpenSSH FAQ page, bug reports, mailing lists, project goals, and a more technical explanation of the security features.
http://www.openssl.org/ — The OpenSSL FAQ page, mailing lists, and a description of the project goal.
http://www.freessh.org/ — SSH client software for other platforms.
Red Hat Enterprise Linux Reference Guide — Learn the event sequence of an SSH connection, review a list of configuration files, and discover how SSH can be used for X forwarding.