source: www.securityspace.com

Title: X Display Manager Control Protocol (XDMCP)
ID: 10891
Category: Useless services
URL: http://www.securityspace.com/smysecu....html?id=10891
Summary: Checks if XDM has XDMCP protocol enabled
Description:
The plugin sends a XDMCP QUERY request to see if the remote
host is running XDM (or similar display manager) with XDMCP
protocol enabled. This protocol was used to provide X display connections for old
X terminals. XDMCP is completely insecure, since the traffic and
passwords are not encrypted.

Risk factor : Medium
Solution : Disable XDMCP