Launching Firefox from a snapd installation in Lubuntu to an xdisplay server using Putty, X11 forwarding and Xming
The purpose of this article is to record and summarise the process to setup X11 forwarding with Putty and a Lubuntu installation so that a GUI based application can be executed on the same system as the putty client. Most setups worked for native usr binaries such as xclock, xeyes (located in the /usr/bin/xclock) directory but for applications located in other directories such as /snap/bin the following error is shown below:
PuTTY X11 proxy: Unsupported authorisation protocol
Error: cannot open display: [PCNAME]:10.0
Copying the .Xauthority file to the root home directory did not work.
But launching with the XAUTHORITY=$HOME/.Xauthority /path/to/binary-file command worked.
e.g. XAUTHORITY=$HOME/.Xauthority /snap/bin/firefox
Simple rough steps:
Install Lubuntu
Install OpenSSH
apt install openssh-server -y
systemctl enable ssh
Allow port 22
sudo ufw allow ssh
sudo ufw enable
Download, install and launch Xming and fonts (fonts optional)
https://sourceforge.net/projects/xming/files/Xming/6.9.0.31/
https://sourceforge.net/projects/xming/files/Xming-fonts/7.7.0.10/
Configure Putty session with X11 forwarding
Before -->
Webpage URL with the full details: https://appuals.com/putty-x11-proxy-error/
Configure sshd_config as follows
sudo vi /etc/ssh/sshd_config
Make the following changes. Uncomment as necessary as save.
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost no
PrintMotd no
TCPKeepAlive yes
NB: DO NOT add the following entry in the sshd_config file as the ssh server will report an error and may not start.
ForwardX11Trusted yes <-- DO NOT ADD IN FILE
Restart services as required
sudo systemctl restart ssh.service
Forum Post on X11 forwarding and launching /snap/bin/firefox
https://www.reddit.com/r/linuxquestions/comments/wypz4v/x11_forwarding_question/
Never mind, I figured it out.
22.04 installs firefox as a snap by default and that does not
correctly handle xauth authentication. I installed a non-snap version
and it now works as expected. It also works with the snap version if I
run
XAUTHORITY=$HOME/.Xauthority /snap/bin/firefox
Additional troubleshooting steps to determine xauth is working
https://stackoverflow.com/questions/46277419/x11-proxy-unsupported-and-wrong
Launching another instance of X
https://unix.stackexchange.com/questions/85383/how-to-start-a-second-x-session
startx -- :1
NB: To be done in a console not in a putty/TTY session.
How to find the list of GUI applications in a Linux installation
https://askubuntu.com/questions/1091235/how-to-get-the-list-of-all-application-installed-which-has-gui
Naresh
20230611
