Displaying a Login Screen on a Network Display

The login server can accept requests from network displays to display a login screen on that particular display. The network display is usually an X terminal but can also be a workstation.

To manage requests from network displays, the login server supports the X Display Manager Protocol (XDMCP) 1.0. This protocol enables the login server to negotiate and accept or reject requests from network displays. Most X terminals have XDMCP built in.

XDMCP Direct Requests from Network Displays

When you configure your X terminal to use XDMCP direct (query mode), you tell your X terminal the host name of the login server host. When the X terminal is booted, it automatically contacts the login server, and the login server displays a login screen on the X terminal. See your X terminal documentation for information describing how to configure your X terminal for XDMCP direct mode.

Most X servers also support the -query option. In this mode, your X server behaves as if it were an X terminal, contacting the login server host directly and requesting that it display a login screen on the X server. For example, starting the X server on a bitmap display on workstation bridget will have login server anita display a login screen on the X server:

X -query anita

XDMCP Indirect Requests from Network Display

When you configure your X terminal to use XDMCP indirect mode, you tell your X terminal the host name of the login server host. When the X terminal is booted, it will contact the login server, and the login server will present a list, through a chooser screen, of other login server hosts on the network. From this list, the user can select a host, and that host will display a login screen on the user's X terminal. See your X terminal documentation for information describing how to configure your X terminal for XDMCP indirect mode.

As with direct mode, most X servers support the -indirect option, which causes your X server to contact the login server in XDMCP indirect mode.

Managing Non-XDMCP Network Displays

Older X terminals may not support XDMCP. For the login server to display a login screen on this type of X terminal, list the X terminal name in the Xservers file.

Since the display is on the network, display_name includes the host name as part of the name. The display class can be used to specify resources specific to a particular class of X terminals. (Your X terminal documentation should tell you the display class of your X terminal.) The display_type of foreign tells the login server to connect to an existing X server rather than to start its own. In this case, an X_server_command is not specified.

Example

The following lines in the Xservers file direct the login server to display a login screen on two non-XDMCP X terminals, ruby and wolfie:

ruby.blackdog.com:0 AcmeXsta foreign 
wolfie:0 PandaCo foreign