Accessing Statslab Systems Remotely

Introduction

Many people have asked me for help with using their own computers to access Statslab machines from their home or college. I am not the best person to ask about this, because it is very difficult to provide in-depth support when I cannot sit at your computer and see exactly what it is doing wrong. If the machine you are using is administered by someone else, you will do better asking them (e.g., if you are using a college machine, your college Computer Officer will be able to give you more help than I can).

There are many activities which fall under the general heading of ``remote access'', including the following:

There are also many operating systems which your home computer might be running. This document mostly covers Linux and Windows because I do not know much about Macs (although since MacOS is a Unix, anything involving the command line will be the same as for Linux). Matt Parry has kindly contributed some information on the Mail on Macs email client. If you use a Macintosh, or some more obscure system, and wish to write your own web page about connecting to the Statslab from it, please let me know and I'll add a link to your instructions.

When You Can't Connect

If you have been able to ssh in before but it isn't working now, the machine you are trying to connect to may have been switched off to save energy. If so, you can either use an alternative computer, or ssh into primrose and type ``wake yukon'' replacing ``yukon'' with the name of your computer. I have a web page with more information on energy saving including a link to a complete list of Statslab computers.

Logging in via ssh

If you are using a Mac or Linux/Unix machine, then gaining full graphical access to the Statslab is simple. You need only pop up a terminal window and type ``ssh -X username@yukon.statslab.cam.ac.uk'' replacing ``username'' with your own username and optionally replacing ``yukon'' with any other Statslab computer. You will get a warning message the first time you connect to a specific Statslab machine, but if you choose to continue connecting, you won't get the message next time you connect to that machine.

If you get a ``Command not found'' error message, you probably need to install ssh. The -X option should enable you to run graphical applications over the network regardless of your computer's ssh configuration, but this has been known to fail on Macs. If this happens please email help@maths.

For Windows users who require full graphical access to Linux machines, DAMTP have written a local piece of software called WineX which can be used to launch a remote graphical session on a Maths Linux system as if you were sitting at the console. Statslab users should switch to the "Unix X environment" tab and ensure that the Statslab radio button is selected. (There are other programs which serve a similar purpose, for example Exceed, Xming and Cygwin, but these are no longer supported.)

Windows users who only require a text-based Linux session can download PuTTY, a Windows ssh client. First go to the Colours tab and change the default foreground to black and the default background to white (or any other combination you like - I find the default colour combination ugly and difficult to read). Then go to the Connection tab, select the ssh button and type in the name of the machine you want to connect to, and click Open to connect. To save your settings for connections to a particular machine, type a name into the Session Name box and click Save. Then when you want to connect to the same machine again, all you need to do is click on your session name and then Load before clicking Open.

Reading and Sending Email

The simplest ways to access your email are to ssh in and use pine or mutt and to make use of our webmail service. If you wish to read your email using a mail client, here are step-by-step guides to configuring If you are using an older version of any of these clients, you are advised to upgrade if possible. If you are using a completely different client, it may be useful to know that our IMAP and SMTP servers are mail.statslab.cam.ac.uk. Please configure your client to use secure IMAP and SMTP (imaps on port 993 and smtps on port 465) if possible.

Thunderbird and Eudora OSE

Highlight the account name, click "View settings for this account" and click "Server Settings". Ensure that the connection security is set to SSL/TLS. Server Settings
Also click on "Outgoing Server (SMTP)" then "Edit". As before, set the connection security to SSL/TLS. SMTP server

Outlook Express

Tools -> Accounts -> Properties -> Servers. Tick "My server requires authentication". Under "Settings" be sure that "Use same settings as my incoming mail server" is ticked. Server settings
Also Tools -> Accounts -> Properties -> Advanced and under both SMTP and IMAP, tick "This server requires a secure connection (SSL)". Change the port number for outgoing mail from 25 to 465. Advanced server settings

Outlook

If running the Startup Wizard, do not enter your name and email address when first requested. Select "Manually configure server settings or additional server types". Under "Choose Service" leave Internet Email selected.

To modify an existing account, File -> Info -> Account Settings, highlight the account and click Change. You should now be at the first dialog box displayed below.

Set the Account Type to IMAP and the incoming and outgoing mail servers to mail.statslab.cam.ac.uk. Add New Account
Click on More Settings then Advanced and configure Outlook to use encrypted connections as shown. Change the port number for the outgoing server from 25 to 587. Server Port Numbers
Also click on Outgoing Server and ensure that "My outgoing server (SMTP) requires authentication" and "Use same settings as my incoming mail server" are selected. Outgoing Server

Matt Parry has contributed the following:

For Mail on Macs:

Accessing Restricted Web Pages

Often access to a website is controlled by a password - for Cambridge websites Raven is generally used, and you are advised to apply for a Raven password if you do not have one already. This is convenient because it allows you to access the website from any computer in the world.

However, you may still come across websites which will only permit access from computers within certain domains such as cam.ac.uk or statslab.cam.ac.uk. If you want to access these websites from your home computer, you can ``tunnel'' the web traffic over ssh. You will need a browser which supports automatic proxy configuration scripts e.g. a modern version of Firefox or Internet Explorer.

To set up the tunnel, run the following command: 

ssh -X -D 9870 username@primrose.statslab.cam.ac.uk

(Replace ``username'' by your username, and there is nothing special about primrose except that it is always switched on. Also, you may want to create a short alias for this command.)

Windows users can type the same command with ``plink'' in place of ``ssh'' (plink is the command-line version of PuTTY) or use Jon Peatfield's helpful instructions with diagrams to save a PuTTY session to do the tunnelling automatically.

There are two proxy configuration scripts you can use. If you want to view Cambridge (including Statslab) pages as if from a local machine, while browsing pages outside Cambridge directly, then use: 

http://www.damtp.cam.ac.uk/conf/proxyCAMtun.pac

If you want to view all web pages as if from a Statslab machine (some journals' websites can only be viewed from computers in certain domains including cam.ac.uk), you need to use a different automatica configuration script: 

http://www.damtp.cam.ac.uk/conf/proxyALLtun.pac

When you don't need to access restricted pages, you might wish to turn the tunnelling off and browse the web directly to speed things up. You can do this by changing the proxy settings every time, but it is somewhat tedious. If you use a modern version of Firefox or Seamonkey, you can also do it by setting up one profile to use the proxy autoconfig script for tunnelling, and the other profile to access the Internet directly (or however your ISP recommends).

Copying Files

Windows users can copy files over the net using the free program WinSCP. Once you have installed WinSCP, and connected to the Statslab by entering the name of a Statslab machine and your username and password, a list of your Statslab files will be displayed in a window. You can copy them to your home machine by dragging them, or simply open them by double-clicking as you would for a local file. (N.B. This will not work for plain text files unless they have the extension .txt.)

WinSCP will often get confused if your .bashrc or .cshrc file produces any output. The best fix is to move the commands that produce the output to .bash_profile (for bash users) or .login (for csh/tcsh users). If all that is gibberish to you and you haven't edited any of those hidden files yourself, ssh/putty into a Statslab machine and type ``/alt/bin/shellreset''.

Linux users can copy files from the command line using scp. E.g. if I wanted to transfer a copy of my file UKPA.jpg to my home Linux computer I would type 

scp eva@solstice.statslab.cam.ac.uk:/home/eva/UKPA.jpg .
(the dot is important - it means "copy to the current directory"). You can copy a whole directory with ``scp -r''.

Alternatively, if you use Gnome/nautilus on your home computer, you can see your Statslab files in a graphical window and transfer them by dragging and dropping. Select "Connect to Server" from the Places menu. Select SSH for the service type, enter a Statslab machine name in the "Server" box, your home directory in "Folder" and your username in "User Name".

Connect to Server dialog box

You can then view, edit and copy your Statslab files as if they were on your local computer. When you have finished, it's a good idea to disconnect by right-clicking on the new icon which appeared on your desktop when you connected, then choosing "Unmount".

This document was written by the Statistical Laboratory Computer Officer, Eva Myers (eva@statslab.cam.ac.uk). It is available online at http://www.statslab.cam.ac.uk/~eva/remoteaccess.html .

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