libxdmcp-dev 1:1.1.0-4 (amd64 binary) in ubuntu precise

 This package provides the main interface to the X11 display manager control
 protocol library, which allows for remote logins to display managers.
 .
 This package contains the development headers for the library found in
 libxdmcp6. Non-developers likely have little use for this package.
 .
 More information about X.Org can be found at:
 <URL:http://www.X.org>
 .
 This module can be found at
 git://anongit.freedesktop.org/git/xorg/lib/libXdmcp