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UCL Home  /  Geography  /  Resources  /  Computer Support  /  Linux Remote Access

Linux Remote Access

Introduction

The Linux Teaching Cluster systems can be accessed remotely for use in the evenings and weekends. The basic method is to connect (using Secure Shell, SSH) to one of the gateway secure servers, and from there to the internal system (for example, a teaching cluster workstation) you wish to use. The added complication is getting the display (of the target system) piped through the SSH connection so it shows on your own system.

It's worth noting that you shouldn't run programs on the gateway systems. Not only do they not have much useful software installed, but if you make one run slowly you'll be affecting other people also trying to use it for remote access. Please just connect to the internal system you want and run programs there.

The instructions vary a little according to the operating system you're using, but the systems you connect to will be the same. These are:

Gateway Servers

archibald.geog.ucl.ac.uk
roundabout.geog.ucl.ac.uk
squarepeg.geog.ucl.ac.uk
triangleting.geog.ucl.ac.uk

Teaching Cluster Workstations

ankara.geog.ucl.ac.uk 
bangkok.geog.ucl.ac.uk
caracas.geog.ucl.ac.uk
dakar.geog.ucl.ac.uk
edinburgh.geog.ucl.ac.uk
freetown.geog.ucl.ac.uk
gaborone.geog.ucl.ac.uk
hanoi.geog.ucl.ac.uk
islamabad.geog.ucl.ac.uk
khartoum.geog.ucl.ac.uk
lima.geog.ucl.ac.uk
muscat.geog.ucl.ac.uk
nassau.geog.ucl.ac.uk
ottawa.geog.ucl.ac.uk
pyongyang.geog.ucl.ac.uk
quito.geog.ucl.ac.uk
rabat.geog.ucl.ac.uk
seoul.geog.ucl.ac.uk
tirana.geog.ucl.ac.uk
ulanbator.geog.ucl.ac.uk
valletta.geog.ucl.ac.uk
washington.geog.ucl.ac.uk

 

Windows

There are two pieces of software to download and install, Putty (choose the "Windows installer" download here) and Xming. With Xming, you need to run the program "Xlaunch" - it'll ask you a few questions, and then run in the background. The only tricky part with this setup is getting Putty and Xming to play together, and this is through a checkbox in the Putty configuration (Connection -> SSH -> X11, check "Enable X Forwarding").

Once you've connected to a gateway server using Putty, you need to connect to a Teaching Cluster workstation, using a command of the form:

ssh -Y username@<target server>

Where <target server> is one of the Teaching Cluster workstations.  That -Y is the part that tells SSH to put the display onto your screen.

Mac

Mac users have it a little easier than Windows users, they only have to install one piece of software, XQuartz. Once installed, they have the same two steps - connect to the gateway, then connect to the target server. Unlike with Windows, this is all using the terminal, there's no GUI to play with.

The first SSH connection should be of the form:

ssh -Y username@<gateway server> 

The second should be of the form:

ssh -Y username@<target server> 

Where <gateway server> is one of the gateway servers, and <target server> is one of the Teaching Cluster workstations.  That -Y is the part that tells SSH to put the display onto your screen.

Linux

Linux users can be a bit smug. While Windows users have to download two bits of software, and mac users have to download one, Linux users have everything they need already. Sweet. All you need to do is ssh to the gateway system and then ssh to the target system, and... that's it!

The first SSH connection should be of the form:

ssh -Y username@<gateway server> 

The second should be of the form:

ssh -Y username@<target server> 

Where <gateway server> is one of the gateway servers, and <target server> is one of the Teaching Cluster workstations.  That -Y is the part that tells SSH to put the display onto your screen.

Here's a cut and paste of my session:

-bash-4.1$ ssh -Y test2015@triangle.geog.ucl.ac.uk
The authenticity of host 'triangle.geog.ucl.ac.uk (128.40.199.15)' can't be established.
RSA key fingerprint is d1:a1:47:2f:a0:98:4d:04:29:1b:aa:46:55:3c:84:23.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'triangle.geog.ucl.ac.uk' (RSA) to the list of known hosts.
test2015@triangle.geog.ucl.ac.uk's password:
-bash-4.1$ ssh -Y quito
test2015@quito's password:
Last login: Tue Sep 22 15:58:20 2015 from square.geog.ucl.ac.uk
-bash-4.1$

 

What Next?

Now you're connected you can run programs on the Teaching Cluster system and have their display appear on your own system. This means that the window that appears is not of a program on your system, it's of a program on the workstation you've logged in to.

So if you run "ipython notebook", the software will be running on the workstation in the North-West Wing, but the Firefox you'd normally see in the Cluster Room will actually appear on your own system at home (or wherever). One confusing aspect is that as this is the Firefox on the Teaching Cluster system, you won't have any of your normal bookmarks. Any bookmarks you make on this Firefox will be visible on any Teaching Cluster workstation (on your login), or the next time you connect in this way.

If you run "gedit" (a basic text editing program), the files you'll be able tedit aren't the ones on your home system, but the ones on the Geography Linux storage systems - the same as in the Teaching Cluster.

Lastly, you can run "win7vm" to run the Windows Virtual Machine on the workstation. Only one of these can be run on each workstation, so it's possible you'll try to run it at the same time as someone else and be told it's already in use. In this case, log out of the workstation and try another.