XDMCP is a handy tool for graphical login into Linux from Windows workstation. I use Xming for that. But before you could login you have to do some extra configurations.
First thing to do is enabling XDMCP in /usr/share/gdm/defaults.conf. Add following line under [xdmcp] section:
Enable=true
And second is opening firewall ports. XDMCP works through UDP 177, TCP 6000-6005 and TCP 7100. I did that from graphical interface. If you don’t have access to graphics then edit /etc/sysconfig/iptables.
Don’t forget to restart X server.
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