Learning Red Hat Linux

Configuring a Secure Shell Server

A secure shell server lets you connect to a system from another system, via TCP/IP, and obtain a shell prompt, from which you can issue commands and view output. You may not be familiar with secure shell servers, but familiar with Telnet, which works similarly. A secure shell server differs from a Telnet server in that the conversation between a secure shell server and its clients is sent in encrypted form so that hackers cannot easily discover private information, including userids and passwords.

The secure shell client and server cannot be distributed on a CD, because they utilize advanced encryption techniques; U.S. law currently forbids general distribution of such software. Therefore, you must download the client and server from SSH Protocols’ web site in Finland, http://www.ssh.fi/sshprotocols2/. At the time of this writing, you could somewhat more conveniently download the client and server from Replay Associate’s web site, http://www.replay.com/redhat/ssh.html. Replay Associate’s web site includes RPM files, making it easy to complete the installation. The secure shell client and server are free for non-commercial and educational use.

To start the secure shell server, you must reboot your system. Alternatively, you can log in as root and issue the command:

/etc/rc.d/init.d/sshd start

You can verify that the server has properly started by issuing the command:

/etc/rc.d/init.d/sshd status

The command’s output should report that ...