ssh and sudo but no $DISPLAY

ssh x11 xorg xforwarding

17,764

Solution 1

Solution found. An alternative method copied from this blog Using this script

userfirst=sshloginuser
usersecond=sudoorsuuser

$usersecond@host$

    su - $userfirst -c 'xauth list' |\
         grep `echo $DISPLAY |\
             cut -d ':' -f 2 |\
             cut -d '.' -f 1 |\
             sed -e s/^/:/`  |\
         xargs -n 3 xauth add

Or simply Logging as user1

xauth list

su or sudo su user2

xauth add OUTPUTOFXAUTHLIST

Solution 2

Another solution is to merge the .Xauthority file of the current user with that of the root user.

ssh user@host
change the .Xauthority file permissions so that root also has access to it.
sudo su - root
xauth merge /home/users/user/.Xauthority

Test

gedit somefile.log

It should open a gedit window.

Solution 3

to make the solution permanent you can modify the .bashrc file of the login user adding

if [ -z "$XAUTHORITY" ]; then
    export XAUTHORITY=$HOME/.Xauthority
fi

moreover you have to update your sudoers file adding the row

Defaults env_keep+="DISPLAY XAUTHORITY"

if root has read permissions on the login user's .Xauthority file you'll be able to use X applications.

Solution 4

This might be an old post, but I solved this permanently linking (in server) my sudoer user .Xauthority file with the root one:

sudo ln -s /home/userWithPrivileges/.Xauthority /root/.Xauthority

This way I don't have to do anything else ever, I can now launch any GUI app with or without sudo.

Solution 5

A very simple generic command:

sudo xauth merge /home/$USER/.Xauthority

This activates the root environment and merges the xauth info of the current (non root) user.

Another alternative, should prevent ownership problem reported in the comments on Slackware:

cat ~/.Xauthority | sudo xauth merge -

View more solutions

17,764

elbarna

Updated on September 18, 2022

Comments

elbarna over 1 year
Usually I do this on ssh for getting a X application using sudo su
```
ssh -X server
```
OKI login
```
xauth list $DISPLAY
```
which returns to me
```
server/unix:10  MIT-MAGIC-COOKIE-1  blablablablabla
```
Then I do
```
sudo su
xauth add server/unix:10  MIT-MAGIC-COOKIE-1  blablablablabla
```
And after running an X application..I get it, it is correct.

The problem is on Centos7, I do
```
xauth list $DISPLAY
```
And it returns nothing. I try to add MIT magic cookies given by
```
xauth list
```
But of course it doesn't work. The normal X-forwarding via ssh, without sudo works.

The settings of sshd are the same on 3 servers:
1. slackware WORKS
2. hpux WORKS
3. centos7 NOT WORKING
HomeIsWhereThePcIs over 3 years

Could you elaborate a little more what this does exactly, and what the security implications of using this are?
elbarna almost 3 years

I confirm the problem on Slackware current ls -lhd .Xauthority -rw------- 1 myuser myuser 63 2021-07-21 21:46 .Xauthority sudo xauth merge /home/$USER/.Xauthority ls -lhd .Xauthority -rw------- 1 root root 63 2021-07-22 21:50 .Xauthority
user1656671 almost 3 years

Please check the alternative above that passes .Xauthorith via stdin. Should prevent ownership changes.
elbarna almost 3 years

It fails $ cat ~/.Xauthority | sudo xauth merge - $ xmms No protocol specified ** CRITICAL **: Unable to open display $ ls -lhd .Xauthority -rw------- 1 root root 255 2021-07-27 01:04 .Xauthority
user1656671 almost 3 years

I would suggest to check $DISPLAY is defined. Maybe copy .Xautority to a temp file and merging with the temp file. e.g. cp /home/$USER/.Xauthority /home/$USER/Xauthority.tmp ; sudo xauth merge /home/$USER/Xauthority.tmp ; rm /home/$USER/Xauthority.tmp