Computational Physics 2007 > Network access

Network access to PWF Linux from Microsoft Windows

If your local machine is running some version of MS Windows, then the route to a secure X Windows connection to the PWF Linux server is more complicated. You will need an X server program for Windows (such as Exceed, available for institutional use from Computing Service Sales for a small licence fee); and also an SSH client, such as PuTTy. Note that the alternative Tera Term with the TTSSH extension, which was previously recommended, only supports version 1 of the SSH protocol and is no longer compatible with the PWF Linux systems. Exceed and PuTTy may already be installed on your college machines, and are installed with Windows XP on the Physics PWF workstations if you want to see them in action: look in the PWF Programs -> Communications and Networking folder.

Configuring Exceed

The X server should be configured to start up in passive mode, accepting connections from the local host only. Run the Exceed configuration tool xconfig and:

• Select Security, set "Host access control list" to "File", select "Edit" and add the single line "localhost"
  to the end of the xhost.txt file in the notepad window that opens. This should be the only line in the
  file that does not start with the comment character `#'. Save the contents and close the notepad window.
• Select Communications, and set the startup mode to "Passive".
• Select Screen Definition, and set the window mode to "Multiple".

Now when you start Exceed, it should run in the background without offering any direct login prompt.

Configuring PuTTy

PuTTy is a small program written by a team of Cambridge programmers. When you have downloaded and installed it from the link above, configure it as follows:

• Run putty.exe. Depending on how you have installed it, there may be an entry for Putty in the Program menu.
  The left-hand pane of the putty window contains links to various configuration options. They form a tree arrangement, where branches are expanded by selecting the "+" symbols.
• Select the "Connection" -> "SSH" -> "Tunnels" screen.
  • Check "Enable X11 forwarding".
• Select the "Connection" -> "SSH" screen.
  • Select "2" as the "Preferred SSH protocol version".
• Select the "Session" screen.
  • Select "SSH" as the "Protocol".
  • Highlight "Default Settings" and select "Save" to save all of these changes as the defaults for next
    time you open PuTTy.

Now you should be able to start up a remote X windows session on the PWF server:

• Start Exceed, which should run passively in the background.
• Start PuTTy, and make sure that SSH is the selected protocol.
  Enter linux.phy.pwf.cam.ac.uk in the hostname box, and click "Open".
• You should then get a login box for the PWF Linux server: enter your username and password and click "OK".
• You should now be logged in with the usual shell prompt, and be able to run X windows applications such as xterm and emacs to your local screen.

If you have problems gaining access via MS Windows from your college machines, then your College Computer Officer may be able to help.