Launching Firefox (with a snapd installation) in Lubuntu to an xdisplay server using Putty, X11 forwarding and Xming

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 -->

After -->

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