SSH public key authentication

JASMIN employs SSH public key authentication for login instead of username and password. This article provides a basic overview of public key authentication.

Public key authentication (for SSH)  

SSH stands for “Secure Shell”, a protocol that allows login to another computer over the network. This allows the user to execute commands on a remote machine. SSH uses encryption to keep the connection secure so that it is more difficult for hackers to passwords or other sensitive information that may pass through the connection.

Public key authentication is an alternative means of identifying yourself to a login server, instead of typing a password. It is more secure and flexible, but can appear more difficult for new users.

Why is public key authentication more secure than a password?  

When using conventional username/password authentication you will type your password when you log on to a server. If the server you are working on has been compromised then an attacker could learn your password and then use it to gain access to the remote server you are connecting to.

With public key authentication, the private key is kept only on your own machine and the passphrase to unlock it is entered there too. An attacker would require both knowledge of the passphrase used to protect your private key as well as the private key file itself.

Public key authentication setup  

Setting up SSH keys involves the following steps:

1. Create a pair of SSH keys (public and private with associated passphrase ).
2. Provide the public key to remote machines/services that you wish to login to.

See instructions for setting this up on JASMIN.

Login with your SSH key pair  

Once you have set up your key pair and provided your public key to the remote machine the process is as follows:

1. Load the private key into an “authentication agent” (such as ssh-agent) on your local machine.
2. Use an SSH client (such as the ssh command) to login to the remote server.

See instructions for setting this up on JASMIN.

Logging in from multiple machines  

If you have a requirement to login to your JASMIN account from multiple servers/locations then please copy your private key file securely to the ~/.ssh directory on the new machine. Note that you should restrict access the private key so it is only readable by you.

Using public key authentication with other applications  

Many other tools use the SSH protocol for their communication with remote servers or services, for example rsync, scp, git and subversion.