Red Hat Enterprise Linux 6 is different from Red hat Enterprise Linux 5.X
1. Open /etc/gdm/custom.conf and edit the security and xdmcp section like the followings:
[security]
DisallowTCP=false
[xdmcp]
Enable=true ;其实只添加这行也可以
Port=177
2. Add UDP port 177 to the Allow list on firewall.
防火墙关闭的就不用修改
/etc/sysconfig/ipchains文件中加入以下语句：
-A input -p udp -s 0/0 -d 0/0 177 -j accept
3. As an admin, do 'init 3' and then, 'init 5'
修改/etc/inittab，将
id:3:initdefault:
修改为：
id:5:initdefault:
If you have enabled XDMCP and open UDP 177 on the server, make sure gdm is running. Use 'ps -aef | grep dm' and it should give you the display manager that is running on the server.
If it it not running, please make sure the display manager such as gdm or kdm is installed on the machine. Red Hat 6 does not install display manager by default.
如果改完了不好用请重起一下机器就OK了