SSH and Remote Connections

How to remotely connect to the Universitiy's UNIX and Linux multi-user computers.

Remotely Connecting to the University's UNIX and Linux Computers

The university's UNIX and Linux servers can be connected to remotely from (in general - restrictions apply*) anywhere connected to the internet. A remote connection can be in the form of a text based command line interface or a graphical connection via X windows or VNC.

* Some servers, notably the Solaris ones, require your computer to have a valid DNS entry to connect. If you cannot connect to these servers, this could be a possible problem, which can (and should) be resolved by your internet provider.

Text based connections

Yes, despite graphical interfaces been invented in the 1970s, some of us still like to type white textual comands in to a black screen.

Linux / UNIX users

You probably know how to do this already, but typically to connect to a server a command such as...

ssh <USERNAME>@vega.dur.ac.uk

...is used to connect to the Linux server Vega as <USERNAME>.

Windows Users

Windows does not come with support for SSH connections (those typically used to establish a link to UNIX/Linux servers) built-in; however there are many pieces of software to fill this gap. A common, and free, program that can be used for this purpose is PuTTY. Instructions for configuring PuTTY are described below.

PuTTY

PuTTY can be downloaded, free of charge, from the PuTTY homepage we recommend you download the "Windows installer" version on Windows.

After installation a folder called "PuTTY" should have been added to the start menu, within this the program "PuTTY" is used to connect to the university's servers.

Starting PuTTY brings up a dialogue asking for details of the server to connect to. Simply typing the name of the server in the "Host Name" box and clicking open will connect to the server.
                          
If you use PuTTY often, or if you go on to change other settings before connecting, you may find it useful to save the connection details. Saving and loading settings is done from the main screen that starts up when PuTTY loads, which can be found under"Sessions" in the left hand menu. To save the details of a connection type a name to remember them by in the "Saved Sessions" box and click "Save". To recall the settings later you can double click the item in list (which will connect directly), or click on it and select the "Load" button to be able to edit it.

After clicking "Open", PuTTY will connect to the server specified in the "Host Name" field. This process may take a few seconds, after which you will be asked to login. Type your username, press return (enter) and then, when asked, type your password and press return (enter). Whilst you username is shown as you type it, your password is not usually shown for security reasons.

After a few seconds you should be presented with any "messages of the day" that ITS provide and potentially other pieces of information dependant on the computer you have logged in to. You should then be able to issue commands asnormal.

To logoff type "logoff" at the comment line, closing the window will not log off you off the server.

Graphical Connections

So, you want pictures too?

There are several possible ways to connect to the university's computers with a graphical rather than text based connection. Unfortunately remotely accessing windows based  servers is limited to a library server which provides various CDROM titles and there are no generally available windows terminal servers to connect to. Unix and Linux servers can beconnected to via several methods, the generally implemented X Windows (not to be confused with Microsoft Windows) is available, but setting it up is outside the scope of this article. Analternative (and much simpler) method is to use Real VNC and the Linux servers.

Real VNC

Real VNC is a piece of software to remotely view and control another computer and is easy to set up and use. It can be downloaded from www.realvnc.com (search for the free edition,it's harder to find than the other versions) and installs on any system.

Unix and Linux users may already have a VNC client installed,though they can be labelled different on different installations.

Due to firewall restrictions at the university, it is necessaryto set up a "tunnel" between your computer and thelinux server you wish to connect to. This can be done with most SSH clients in a similar way to that described above to connectto a text based server.

Windows

On windows, PuTTY can be used to create the necessary tunnel. The connection is established in an identical way to the method described above, but with one additional step.

This step comes between entering a host name and connecting to the server. As this set may take a few moment, you may want to save the settings afterwards as described above.

It does not matter the computer you enter in the host name, provided it is within the Durham network. For performance reasons, however, we recommend it is the same as the server you wish to connect Real VNC to. ITS provide these services on this vega.dur.ac.uk cluster, but not the solaris servers (altair.dur.ac.uk and deneb.dur.ac.uk).

After connecting to the server and logging in, the tunnel will be set up. You can them start Real VNC and instruct it to connect to "localost", which should bring up the remote server screen.