Fox-specific Information for SSH

ssh is a command line utility which allows you to log in to other machines remotely.

Some cluster-specific SSH information is documented below. For more in-depth details, and other command-line options, please consult the complete man pages with man ssh.

Logging in to Fox may only be done with a username and password. Login via SSH keys is not possible.

SHA256 fingerprint

You will need to confirm that the connection shall be trusted. The first time you log in to a machine via ssh, you will get a message like

The authenticity of host '<hostname>' can't be established.
ECDSA key fingerprint is <fingerprint>.
Are you sure you want to continue connecting (yes/no)?

If the <fingerprint> matches the fingerprint of the login machine you are logging in to (see below), you can confirm by typing yes and pressing Enter. (Note that the trailing ¡°.¡± is not part of the fingerprint.) If the fingerprint does not match, please contact ec-drift@uio.no immediately.

To display all fingerprints for a certain server, you can use the following command on your local machine (Linux or Mac):

$ ssh-keyscan fox.educloud.no | ssh-keygen -l -f - -E md5
# Note: 'md5' can be exchanged with 'sha256' to display that variant

The following table displays the different keys, both as MD5 and SHA256, for fox.educloud.no:

SSH Connection Sharing

If you would like to avoid logging in and authenticating multiple times on Fox, you may use ssh connection sharing.

To start, put the following in your ~/.ssh/config :

Host fox
Hostname fox.educloud.no
User ec-...
ControlPath ~/.ssh/controlsock-%h-%p

(fill in your Educloud user name in the "User") line.

Then start a screen or tmux session on your desktop and in that, run "ssh -M fox" and log in as normal (i.e., enter your password and one-time-code).

As long as this first instance is running, you can simply use ssh fox to get onto fox, without requiring anything else. NOTE The -M flag is only needed the first time. All subsequent logins do not use it.

Behind the scenes ssh reuses the existing connection, spawning a new interactive session on top. Because this is does on top of an already-running connection, there is no need to authenticate again.

The original login instance must be kept running for this to work. If you disconnect from this process, you must authenticate again (remembering to ssh with the -M flag!).

^{CC Attribution: This page is maintained by the University of Oslo IT FFU-BT group. It has either been modified from, or is a derivative of, "SSH" by NRIS under CC-BY-4.0. Changes: Removed most sections of original text.}