2. Accessing the machines

How to log in

CSAR has two interactive machines - wren and newton. We recommend that you use ssh to log into these machines as follows:

ssh wren.cfs.ac.uk

ssh newton.cfs.ac.uk

You will be prompted for a username and password.

Interactive access to fermat and green is not permitted. These are batch only systems, all file editing, job submission etc for these machines should be done from wren.

SSH Clients

If you are using a UNIX workstation you can obtain the source code and README file from ftp://ftp.ssh.com/pub/ssh/. Linux distributions generally come with ssh and will either be automatically installed or available via your package management facility.

Windows users can use either putty which is obtained from http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html or SSH Secure Client which is available to academic users free of charge from http://www.ssh.org/support/downloads/secureshellwks/non-commercial.html.

For further information on ssh see:

• man ssh
• http://www.ssh.org/
• http://www.openssh.org/

X access

If you are using a UNIX workstation, X terminal or PC running X server software (e.g. Exceed), you can access wren and newton and use various X facilities. From an X session you can login as described above. X access should automatically have been enabled. The parameter, DISPLAY, is set correctly when you login unless you override it in a .profile, .cshrc or .login file. You may need to allow access to your display using the xhost command

xhost wren.cfs.ac.uk

xhost newton.cfs.ac.uk

in a terminal window on the workstation. This command tells the workstation to allow other systems to open windows on your screen. This command is not normally necessary on X terminals or PCs.