# X11Proxy

X11Proxy is a lightweight X11 proxy designed for containerized environments. It provides an AF_UNIX socket for Docker containers to connect to the host's X11 display, enabling GUI applications to run inside containers with minimal setup.

## Features

- Proxies X11 connections from a UNIX socket (default: `:5`) to the host's current `$DISPLAY`.
- Simple, minimal codebase.
- Ideal for Docker and other container runtimes.
- No complex configuration required.

## Use Case

Run GUI applications inside Docker containers by exposing a UNIX socket for X11 forwarding.

## Quick Start

### 1. Start X11Proxy

```bash
x11proxy
```
By default, this will listen on `/tmp/.X11-unix/X5` and forward to your current `$DISPLAY`.

### 2. Run a Docker Container

Mount the proxy socket into your container and set `DISPLAY` accordingly:

```bash
docker run -it \
    -e DISPLAY=:5 \
    -v /tmp/.X11-unix/X5:/tmp/.X11-unix/X5 \
    x11-app-image
```

Replace `x11-app-image` with your GUI application's image.

### 3. Example: Running xeyes
```bash
docker run -it \
    -e DISPLAY=:5 \
    -v /tmp/.X11-unix/X5:/tmp/.X11-unix/X5 \
    x11docker/xeyes
```

Alternatively, you can use a custom script such as `hello_xclock.sh` to run `xclock` inside a Docker container:

```bash
./hello_xclock.sh
```

This script should mount the proxy socket and set the `DISPLAY` variable appropriately, demonstrating how to launch GUI applications with minimal setup.

## Security

- The proxy socket is protected by file permissions (0700), ensuring only your user can access it.

- For remote X sessions, valid `xauth` credentials are required. X11Proxy injects these credentials into the connection automatically, so your Docker container does not need to have your `xauth` file.

- Note: X11Proxy does not provide isolation between GUI applications. Once connected, containerized apps can interact with other X11 clients on the same display (e.g. capturing input, reading window contents). This is a known limitation of X11 itself and may be addressed in future versions with optional sandboxing or per-client filtering.

## License

BSD 2-Clause License. See [https://opensource.org/license/bsd-2-clause](https://opensource.org/license/bsd-2-clause) for details.

## Credits

Inspired by [X11Docker](https://github.com/mviereck/x11docker), but with a minimal approach.