ssh (Secure Shell)

The ssh command is used to connect from one Linux/UNIX/MacOSX computer to another securely. E.g. to connect to the machine ssh.maths you would type (replace CRSid by your login name)

ssh -X CRSid@ssh.maths.cam.ac.uk

ssh encrypts its traffic and uses public-key cryptography to prove the identity of the remote machine. It is therefore an improvement on the older commands telnet, rlogin and rsh, which should not be used and are very unlikely to be supported by modern computers.

The -X option means "enable X forwarding" so that you can run graphical applications on the CMS machine.

Note that using X applications over ssh works well only over low latency links. If you experience long delays in application reponses use VNC or hotdesk.

Using ssh also greatly simplifies running X applications remotely since it handles the forwarding of the X connection transparently (and securely). However if you are using a Macbook then in order for your X application to work you will need to download XQuartz.

Similarly, ftp is an insecure way of copying files and has largely been replaced by sftp and scp.

• Why use ssh, syntax of ssh commands
• ssh messages and troubleshooting
• Copying files over the network securely
• ssh tunnelling