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Starting a UNIX/Linux Desktop Using SSH
Technical Note 1818
Last Reviewed 17-Aug-2005
Applies To
Reflection X 2008
Reflection X version 12.0 through 14.x
Summary
Technical Note 1818
Last Reviewed 17-Aug-2005
Applies To
Reflection X 2008
Reflection X version 12.0 through 14.x
Summary
Using XDMCP, users are unable to start a UNIX/Linux desktop, such as CDE (Common Desktop Environment), over SSH. This technical note explains why and provides an alternative way to start the desktop over SSH.
About XDMCP Connections
When remotely starting a UNIX/Linux desktop, XDMCP (X Display Manager Control Protocol) is typically used to establish the connection between the host's XDM daemon and the remote X server (Reflection X). Once the connection has been established, and the user has successfully authenticated, the XDM daemon launches the X client session, which is displayed on the user's workstation.
XDMCP uses UDP (User Datagram Protocol) packets as a transport type.
SSH and XDMCP
Note: Beginning in Reflection 13.0, the SSH connection is called Secure Shell. Earlier Reflection versions called the SSH connection OpenSSH.
SSH provides secure, encrypted communications between a host and a workstation. However, SSH does not support UDP packets, which means that if the host is configured to permit only Secure Shell connections, users cannot connect to the host using XDMCP.
Attempts to use XDMCP to connect to a host that requires SSH will fail and an error message will be displayed.
Workaround
To bypass this problem and start a UNIX/Linux desktop XDM session without using XDMCP, follow the steps below.
Warning: When using this workaround, not all of the UNIX/Linux desktop parameters are set, and users may not be able to exit the desktop session normally. If this happens, users should reset or close Reflection X to terminate the session. This causes no problems for Reflection X, but the host processes for the session might not be terminated properly. If you have concerns about this issue, please talk to your host administrator before proceeding.
- Use Reflection X or Reflection X 2008 to make a Secure Shell terminal connection (such as xterm, hpterm, or ddterm) to the host.
Note: For information about making a connection using Reflection X and Secure Shell, see the online help in Reflection.
- Enter the following command in the terminal window, and then press enter.
Xsession &If a message such as "Xsession: note found" is displayed, Xsession is probably not in the path set for your host account. You will need to enter the full path to Xsession. The paths are typically:
UNIX:
/usr/dt/bin/Xsession &Linux:
/etc/X11/xdm/Xsession &gnome-session & (no path needed)startkde & (no path needed)If you are still unable to start Xsession, it might be located in a different path or XDM may not be running on your host. Use the find command to locate Xsession (find / -name Xsession), or see Technical Note 1229 (section H) for information on determining the status of XDM.
Note: If you experience any typing/keyboard problems,
- Click Settings > Keyboard.
- Disable "Allow clients to remap keyboard."
- Click OK.
Your UNIX/Linux desktop should now be displayed on your workstation through the OpenSSH tunnel.
