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Accessing Polaris

Polaris is a publicly available shell server hosted by OIT's Network Services. Polaris accounts are not generated automatically, and must be requested either by a professor for their class, or by an individual with a reasonable need to access the service. Polaris also hosts lin-web/people.clarkson.edu, which is similar to the Webspace Server.

SSH

SSH Clients

Polaris is a Rocky 9 Linux system, so the use of an SSH client is required. While there are many SSH clients out there, OIT has recommendations.

PuTTY (Windows)

PuTTY has been a standard Windows SSH client for a long time. PuTTY can be found here or by using Ninite or Chocolatey.

PuTTY will open to the Session window, where connections are made. The important parts are the Host Name, Port, and Connection Type.

PuTTY Session Window

Set Host Name to <YOUR_USERNAME>@polaris.clarkson.edu, and Connection Type to SSH. Port should already be set to 22. If you want, you can add a name for this connection under Saved Sessions and click Save. Once all of the information is set correctly, click Open.

PuTTY Session window with Connection Type, Port, and Host Name set

Terminal (Mac/*nux) and Powershell (Windows)

Polaris can also be accessed directly from the shell. Simply run ssh <YOUR_USERNAME>@polaris.clarkson.edu. Windows Powershell may have some quirks, especially surrounding editors, so if you encounter issues, we would recommend exploring other options.

Other Options

If neither of these options work for you, or you are looking for more advanced features, please refer to this AlternativeTo page for additional options. Tabby is a solid mutli-platform option, while Termius is a client for iOS and Android.

Logging into Polaris

Upon connecting to Polaris, you will be greeted by a password prompt. Enter yours, then hit enter. Polaris is protected by Two Factor Auth, so you will also be met with a Duo authentication prompt. For most people, there will only be one option, so type 1, then hit enter. You will recieve a standard Duo notification on your mobile device. Once you accept, you will be in a shell for Polaris.

Extra Credit

If you regularly use Polaris, there are a number of extra steps you can take to make your use of the system easier.

SSH Keys

SSH Keys are a cryptographic method to securely access a remote server using a 'key' stored on your device. All clients we mentioned can both generate and present the keys to Polaris for use.

ssh-keygen and ssh-copy-id

For most terminal systems, ssh-keygen is the command you are looking for. For Mac, Linux, and Powershell, running ssh-keygen and leaving most of the options default will be fine. We still HIGHLY recommended that you set a key passphrase.

Once this is done, you can then run ssh-copy-id <YOUR_USERNAME>@polaris.clarkson.edu, which will copy the key you just generated up to Polaris. You will have to log in and go through Duo, but once you do, the key will be in place, and any future sessions will use the key instead.

PuTTYGen

PuTTYGen is PuTTY's SSH key generator, while Pageant is PuTTY's SSH Key Agent.

The PuTTYGen Window

In PuTTYGen, at the very bottom, there is the type of key and the number of bits. For most cases, the defaults of RSA and 2048 are fine. Click Generate, and you will be asked to move your mouse along the grey box to generate randomness for the cryptographic process. Once that finishes, you will be presented with a complete key.

The PuTTYGen Window after generating a key

The Key Comment field is used to allow human-readable key identifiers, such as the user who generated the key. It's likely you'll want to set this to your username.

For best security practices, it is HIGHLY recommended that you set a key passphrase. This will encrypt the private key.

Once you finish with these, use the Save public key and Save private key buttons to save both keys somewhere. We also recommend copy-pasting the Public key from the top of PuTTYGen into something nearby, as you will need this in a future step, when we add the key to Polaris.

To load these keys into PuTTY, there are two options. They can be loaded in directly, which is likely what you want to do, or you can use Pageant.

To load the key in directly to PuTTY, Load (not open) your Saved Session for Polaris, then in the sidebar, navigate to Connection > SSH > Auth > Credentials. Under Private key file, browse to the location you saved you SSH keys from PuTTYGen and select the private key (the .ppk file).

The PuTTY SSH Key section

Once you have the key in, use the sidebar to navigate back to Session, and Save your session. Your key will now be in place.

Another option is Pageant. Open Pageant, then right click on the icon in the taskbar and select "Add Keys". Navigate to your .ppk file and select it. Pageant will then present that key whenever you try and log in using PuTTY or any other terminal program that supports it.

Adding PuTTYGen Key to Polaris

You will need to log into Polaris and have your public key at hand. On Polaris, copy in and run the following code block.

mkdir -p ~/.ssh
chmod 700 ~/.ssh
touch ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Once this is done, run the following command, making sure you replace <PUBLIC_KEY> with the entire public key string from earlier. The writer of this document recommends copying this command into notepad or a similar editor and modifying it there before pasting it into Polaris shell.

echo '<PUBLIC_KEY>' >> ~/.ssh/authorized_keys
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