XManager5连接CentOS6的方法已经行不通了，那么如何用XManager5连接CentOS7
从Xmanger官网博客得知：
“Gnome in CentOS 7 tries to use local hardware acceleration and this becomes a problem when trying to connect remotely using XDMCP. To avoid this problem, you have to use an alternative display manager (other than ‘gdm’) and desktop environment.”
“This guide explains how you can change the display manager to lightdm from gdm and desktop environment from Gnome to Xfce.”
这就是使用Xfce而不用gdm的原因（仅限CentOS7），嗯，不懂的可以百度一下。
参考：
http://blog.netsarang.com/89/connecting-to-centos-7/
http://blog.csdn.net/lic95/article/details/48948099
http://blog.csdn.net/wuzhimang/article/details/51523867
1.安装源
# yum install epel-release -y
2.安装lightdm
# yum install lightdm -y
3.编写配置文件
# vi /etc/lightdm/lightdm.conf
[XDMCPServer]
enabled=true
port=177
4.设置默认显示为lightdm
# systemctl disable gdm ; systemctl enable lightdm
5.启动lightdm
#systemctl start lightdm
6.安装xfce桌面，
#yum groupinstall -y xfce
7.删除gnome文件
关键的一步，删除gnome文件，不然启动的时候还是gnome而不是xfce
# cd /usr/share/xsessions/
# mkdir bak
# mv gnome* bak
# systemctl restart lightdm
8.将Display Manager切换为lightdm
#systemctl disable gdm && systemctl enable lightdm
9.启动lightdm
#systemctl start lightdm
10.关闭防火墙
#systemctl stop firewalld.service
11、查看可用的中文安装包
# yum list kde*chinese
12、安装中文包
# yum install kde-l10n-Chinese.noarch
13、修改开启启动模式
[root@k8smaster /]# vi /etc/inittab
# multi-user.target: analogous to runlevel 3
graphical.target: analogous to runlevel 5
上面multi-user.target是命令行模式
上面graphical.target图形界面模式
14、设置启动模式
[root@k8smaster /]# systemctl set-default graphical.target