The cluster is behind the SLaM firewall, so to access it you have to ssh to a gateway server first, using your VPN token. From there you can ssh to bignode, which is the node on the cluster on which we submit grid engine jobs.

Note that the first time you connect to a machine, you may see a message like:

The authenticity of host 'sshgw.slam-services.org (sshgw.slam-services.org)' can't be established.
RSA key fingerprint is c0:12:f1:34:86:14:6b:13:04:42:93:0a:10:1a:0a:12.
Are you sure you want to continue connecting (yes/no)?

This just means your computer doesn’t yet recognise the machine it’s connecting to. Just type yes. The next time you log in, you shouldn’t see the message.

If you are using Linux, Mac or other Unix flavour, you will already have an ssh client to enable you to connect to the cluster. If you are on Windows you will probably need to install something. Putty is available on the KCL Windows machines already. If you’re installing something yourself, Mobaxterm has more features, but Putty works just as well. Details can be found in the following sections:

Connecting to the gateway on Windows with Putty
Connecting to the gateway on Windows with MobaXterm
Connecting to the gateway from Linux / Mac / Solaris etc

Once you’ve connected to the gateway, you can go on to connect to bignode

You can find more information about accessing the cluster, including how to change your password, how to get more out of ssh and what to do if your VPN token breaks at: Access and Authentication


Connecting to the Gateway on Windows with Putty

Putty is a free ssh terminal application. You can download the putty.exe file from http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html

It doesn’t require any installation, just save the executable file wherever you like and double click to run it. You should see something like this:

Putty-start

In the Host Name field enter sshgw.slam-services.org
Leave the Port field as 22.
In the Saved Sessions field enter BRC ssghw

Putty should now look like:

Putty-create_session

If you need to be able to use any graphical user interface on the cluster, you’ll need to forward X. This step is optional. Expand Connection -> SSH, and select X11. Check the Enable X11 forwarding. As shown in the image below:

Putty-create_session-x_forwarding

To ensure your session doesn’t timeout due to idle time, you need to enable keep alives.
In the left hand tree-listing, click Connection. Set the Seconds between keepalives field to 300. Check the Enable TCP keepalives:

Putty-create_session-keepalives

Now save these settings so you don’t have to enter them all again next time. Scroll up on the left hand tree-listing, click on Sessions. Now click on the Save button.

Putty-save_session

You should now be able to select the BRC sshgw session from the list, click Load and then click Open. You will be presented with a command line login prompt. Enter your username at the prompt and then your PIN+TokenCode at the password prompt:

Putty-login-password

You are now connected to the gateway and you need to connect to bignode


Connecting to the Gateway on Windows with MobaXterm

Mobaxterm provides as ssh client for Windows, with an X11 server, and also comes with a set of useful Unix commands built in. You can download the free version from http://mobaxterm.mobatek.net/download-home-edition.html. The installer requires admin rights on your machine, but the portable edition is just an executable which you can save somewhere and run.

When you run mobaxterm, you will get a terminal which looks like this:

mobaxterm

You can now follow the instructions in the section on Connecting to the Gateway on Linux to ssh into the SLaM gateway machine.

MobaXterm also allows you to save sessions, access files over ssh via a GUI and other useful features. Have a look at http://mobaxterm.mobatek.net/features.html for more information – there’s a short video tutorial at the bottom of the page which should be enough to get you started.

Important Warning: MobaXterm will ask you if you want to save your password. Make sure you select No! As you’re logging in with the token, your password will be different every time. If you save it, Mobaxterm will automatically send that password next time you log in. It will have a few automated attempts with that password before concluding that it doesn’t work and that can be enough failed logins to lock your account on the gateway. If you do get locked out, just contact us with your username and IP address so we can unlock your account.


Connecting to the Gateway on Linux / Mac / Solaris etc

If you are on Windows, you can use Mobaxterm

On Mac OSX: Applications > Utilities > Terminal

Unity (Ubuntu default): Dash > More Apps > Accessories > Terminal

Gnome: Applications > Accessories > Terminal

I can’t list all flavours of Linux desktop here, but google will help if you can’t figure out how to get at a command line on your machine.

Once you have a terminal, you can just do

ssh $USERNAME@sshgw.slam-services.org

Replacing $USERNAME with your username, obviously. When asked for a password, you should use your PIN followed by a generated VPN token code. These should be typed as one long number, do not put a space or a newline in between them.

If you want to be able to open graphical user interfaces from the remote machine, you’ll need to forward X:

ssh -X $USERNAME@sshgw.slam-services.org

Now that you are connected to the gateway machine, you can go on to connect to bignode


Connecting to Bignode from the gateway

Once you’ve connected to the gateway, you can connect to bignode something like (substituting in your username):

ssh $USERNAME@bignode

When you are prompted for the password, you should enter your cluster password, which will have been sent to you when your account was set up. You should only use your PIN+TokenCode when you are connecting to the gateway.

If you want to forward X to bignode:

ssh -X $USERNAME@bignode


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