xhost: unable to open display ":0.0"

[root@lepus client]# DISPLAY=:0.0
[root@lepus client]# export DISPLAY
[root@lepus client]# xhost +
xhost: unable to open display ":0.0"

yum search tigervnc-server
yum -y install tigervnc-server.x86_64
vncserver
New 'lepus:1 (root)' desktop is lepus:1

再次执行，可以
[root@lepus ~]# DISPLAY=lepus:1
[root@lepus ~]# export DISPLAY
[root@lepus ~]# xhost +
access control disabled, clients can connect from any host