SSH GUI ?

#linux

X11 Forwarding with Docker and AlmaLinux

In this guide, we’ll walk through how to enable X11 forwarding with Docker and AlmaLinux so you can run graphical applications from within a Docker container on your host machine. We’ll use SSH to connect and display applications like gedit on your local X server (e.g., XQuartz for macOS).

Prerequisites

Before starting, ensure the following:

  • Docker is installed on your system.
  • XQuartz is installed on your macOS (or X server on other platforms).
  • Basic knowledge of Docker and SSH.

  1. Install XQuartz (for macOS users).

  2. Start Docker Container

Start an AlmaLinux container with port 22 mapped for SSH access:

docker run --rm -it -p 22:22 almalinux /bin/bash

This runs the AlmaLinux container and opens a bash session. The --rm option ensures the container is removed when it stops, and -p 22:22 maps the SSH port.

  1. Install Required Packages Inside the Container

Inside the running AlmaLinux container, we need to install the necessary packages for SSH and a graphical editor (gedit):

yum install -y openssh-server gedit
  1. Configure SSH for X11 Forwarding

To enable X11 forwarding, you need to configure SSH. Edit the SSH configuration file inside the container:

sed -i 's/#X11Forwarding no/X11Forwarding yes/' /etc/ssh/sshd_config
echo "X11UseLocalhost no" >> /etc/ssh/sshd_config

This enables X11 forwarding and allows connections to be forwarded over the network.

Next, start the SSH service manually:

/usr/sbin/sshd

This forwards the display to your XQuartz server on macOS.

  1. Connect via SSH with X11 Forwarding

Now, from your host machine, you can connect to the container using SSH with X11 forwarding enabled. Open a terminal on your host (macOS) and run:

ssh -X root@localhost -p 22

Enter the root password (if configured earlier), and this will log you into the AlmaLinux container.

  1. Run a Graphical Application (like gedit)

Now that you’re logged into the container, you can run any graphical application that you installed. For example, run:

gedit

The gedit window should appear on your macOS via XQuartz.

  1. Troubleshooting

  • If gedit or other apps don’t display, ensure that XQuartz is running, and that the DISPLAY variable is set correctly.

  • If you see an error related to .Xauthority, create the file manually inside the container:

    touch /root/.Xauthority