[Chapter 12] 12.4 Configuring a Secure Shell Server

12.4 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. The installation script will automatically start the ssh daemon.

12.4.1 Using a Secure Shell Client

To verify that the server is properly running, you can access it via a client on the local system. Issue the following command:

 ssh localhost

The client will attempt to log you onto the local system by using your current userid, and should prompt you for your password. If you supply the correct password, you should see a shell prompt, indicating that the client and server are functioning correctly. Type exit and press Enter to exit the secure shell provided by the client.

12.4.2 Using a Secure Server from a Remote System

To log onto your Linux system from a remote system via the secure shell server, you must install a secure shell client on the remote system. A suitable client for Microsoft Windows 9x systems is ttssh, available from Robert O'Callahan's web site, http://www.zip.com.au/~roca/ttssh.html. Simply download and install ttssh on your Windows system, specify the hostname or IP address of your Linux system and your userid and password, and ttssh will log you onto your Linux system.