Changing the XDMCP UDP 177 Port Number

PROBLEM DESCRIPTION

Because of security policies or firewall configurations, you may need to configure UDP to a different port instead of 177, the default XDMCP port.

Depending on the display manager, the location of the source files are as follow:

xdm -> xdm.config -> DisplayManager.requestPort : 177

gdm -> gdm.conf -> [xcmcp] part Port=177

kdm -> kdmrc -> [xcmdp] part Port=177

dtlogin -> Xconfig -> Dtlogin.requestPort : 177

You can change the port number depending on your requirement.