X Authorization 

Symptom 

$ xterm &
[1] 7290
chaos:$ Xlib: connection to "grace:0.0" refused by server
Xlib: Client is not authorized to connect to Server
xterm Xt error: Can't open display: grace:0.0

Solution 

  1. logout chaos and back to iitrc
  2. use xhost

Trying History 

chaos:$ xhost +
Xlib: connection to "grace:0.0" refused by server
Xlib: Client is not authorized to connect to Server
xhost:  unable to open display "grace:0.0"
chaos:~/bin$ logout
iitrc:~$ xhost +
access control disabled, clients can connect from any host
iitrc:~$ telnet chaos
$ xhost +
access control disabled, clients can connect from any host
xhost:  must be on local machine to enable or disable access control.