4.2.3 XDMCP Connection Definition

For XDMCP connections, the X Display Manager Control Protocol is used to communicate with the XDM (X display manager) running on a particular host. This means that the host controls how the X environment is configured and which clients are run. The host must be configured to support XDMCP. XDMCP sessions reset when you log off of the host.

XDMCP connection name

Enter a name for this connection definition.


Specify the type of XDMCP method to use to send a request over the network to launch the XDM client on a host.



Reset and then send a request to all available hosts based on what you enter for Broadcast Address. Any display manager that is willing to service the request responds.



Reset and then send a request to the X display manager running on a specific host. Use Host name to specify the host name or IP address.



Reset and then send a request to a single initial host. Use Host name to specify the host name or IP address. This host may do one of the following, depending on how it is configured at your site:

  • Provide a dialog box to choose another host.

  • Automatically pass the request to another host.

  • Handle the XDM request itself.

Broadcast Address

By default, the XDMCP broadcast address is255.255.255.255, which is called a "limited broadcast." A limited broadcast is not forwarded by routers. If routers on your network are configured to pass specific subnet broadcasts but not a universal broadcast, changing the default value of may allow the broadcast to reach more subnets.

If you have multiple subnets and you want an XDMCP broadcast to reach all of them, you can specify multiple IP addresses in this text box. Separate the entries with a comma.

The following example will list all of the addresses in the subnet, plus the particular host whose IP address is,

Host names can be used for individual hosts. IP addresses must be used to designate subnet-directed broadcasts.

Host name

Enter a host name or IP address. This option is available when Type is Direct or Indirect.

If Direct is selected, the X server sends a request for the login window to the XDM on the specified host. If Indirect is selected, the X server sends a request to the specified host with the expectation that the request will be forwarded to a number of secondary display managers on different hosts. The initial host (also known as the primary display) may also accept the request. The initial host will then display a "chooser window" that presents a list of available hosts.

Connection timeout

Sets the maximum number of seconds that Reflection X Advantage will try to make an XDMCP connection. A value of 0 is interpreted as an infinite timeout.

Default session

A session must be running before an X client application can be displayed. Use the drop-down list to select a default session definition for this client. If <prompt for session> is selected, you'll be prompted to select a session when you start the client. If the session is not already running, Reflection X Advantage starts it when you start the client.

Automatically start XDMCP session

Select this option if you want the XDMCP connection to start automatically when you start X Manager.