Edit File: xdmcp.xml
<?xml version="1.0" encoding="utf-8"?> <service> <short>XDMCP</short> <description>The X Display Manager Control Protocol (XDMCP) allows to remotely log in to an X desktop environment from any X Window System compatible client.</description> <port port="177" protocol="tcp"/> <port port="177" protocol="udp"/> </service>