Starting in XDMCP Broadcast Startup Mode
The XDMCP Broadcast startup mode sends a UDP broadcast/multicast to hosts on the network to determine which hosts are available to manage your X display. You can broadcast/multicast requests to the hosts listed in the Host List File and/or those referenced by the Broadcast/Multicast Address. The Communication tab of the Xconfig dialog box lets you specify the IP address to which packets to be broadcast/multicast are sent. By default, the Broadcast/Multicast Address is 255.255.255.255. This address represents a broadcast to the entire network. Most TCP/IP transport implementations support this address.
To broadcast on your local network, the Broadcast/Multicast Address must consist of the network portion of your IP address with a host portion set to all 1s (in binary). For example, if your IP address is 192.9.200.6 (a Class C address), the network portion of the address is 192.9.200. To use this as the local network broadcast address, type 192.9.200.255 or 255.255.255.255. Multicast addressing limits the sending of packets to a specific group of hosts. This avoids a broadcast to every host on the network. For example, IPv4 addresses between 224.0.0.0 and 239.255.255.255 are reserved for Class D addresses.
For more information regarding Broadcast/Multicast Address specifications, consult your TCP/IP network software documentation.
To select and configure the XDMCP Broadcast mode:
- Select the Xconfig file in which you want to configure XDMCP Broadcast startup and open the Xconfig dialog box.
- On the Communication page, select XDMCP Broadcast from the Startup Mode drop-down list.
- You can set the following options:
- Use Host List FileEnable this option if you want to broadcast requests to the hosts listed in the Host List File. Click Edit to open the host file in a text editor. Specify the host names or IP address (one per line) of the hosts to which you want the broadcast sent. Click Save when you have made all necessary changes.
- Enable Broadcast/MulticastSpecify the IP address to which packets to be broadcast/multicast are sent.
- AddressSpecify the IP address to which packets to be broadcast are sent. By default, the broadcast address is 255.255.255.254. This address represents a broadcast to the entire network. Most TCP/IP transport implementations support this broadcast address.
- Keep AliveSelect this box if your host supports TCP/IP keep-alive.
- Enable or disable Select First Display Manager as required. If you enable this option, you connect to the first display manager that responds to the broadcast. The login information dialog box prompts you to log in to the host.
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If you disable this setting, the XDMCP Display Manager Chooser window prompts you to select an available host to manage the display. After you make a selection, the login information dialog box prompts you to log in. Once you successfully log in to the host, it starts the X applications specified in the XDM session file (script).
- If necessary, in the Miscellaneous area, set the Display Class or enable XDM authentication and set the XDM authentication key.
- Click OK to save changes and return to the previous dialog box or click Apply and select another tab to continue modifying the Xconfig file.
Related Topics
Configuring XDMCP Startup Modes