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Author SHA1 Message Date
1f27f306a5 Fixed illustration 2025-09-26 15:35:35 +00:00
b93ff1d89f Illustration 2025-09-26 15:31:12 +00:00
3494e69c9f Better README.MD + clean up entrypoint.sh 2025-09-24 23:52:20 +02:00
4ac6cd0634 Mirror 2025-09-24 17:00:38 +02:00
167e80c583 v1.0 2025-09-24 16:10:19 +02:00
f98e5f0333 Debug mode 2025-09-24 15:43:35 +02:00
4714570953 test-ok 2025-09-24 12:58:39 +00:00
4b0a28ef21 debug 2025-09-24 14:46:34 +02:00
51f771e0d7 Fixed typo 2025-09-24 12:23:10 +00:00
1444c24b0d Fixed log 2025-09-24 14:03:42 +02:00
0800c8f700 Clean up 2025-09-24 11:54:34 +00:00
eee12f9651 Better logs and start 2025-09-24 11:46:34 +00:00
0cdeaa5ce8 Fixed folder trailing slash if exist 2025-09-24 13:19:58 +02:00
b020a30429 Fixed logic and added variables 2025-09-24 13:10:27 +02:00
5176ddeae9 Fixed variable order and better log 2025-09-24 12:48:28 +02:00
8 changed files with 220 additions and 98 deletions

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@@ -3,9 +3,7 @@
.gitignore
README.md
LICENSE
VERSION
*.log
*.tmp
.env
docker-compose.yaml
Dockerfile.minimal

9
.env
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@@ -1,4 +1,5 @@
# Socat Proxy Configuration
TARGET_HOST=
TARGET_PORT=
SOCKET_PATH=
TARGET_HOST= # Target hostname/IP to proxy to
TARGET_PORT= # Target port to proxy to
UNIX_SOCKET_NAME= # Name of the socket file
UNIX_SOCKET_PATH= # Path to UNIX socket inside container
HOST_SOCKET_PATH= # Host path for socket mounting

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@@ -1,11 +1,9 @@
FROM alpine:latest
# Install socat and netcat in a single RUN command and clean up cache
RUN apk add --no-cache socat netcat-openbsd \
&& rm -rf /var/cache/apk/* /tmp/*
# Create socket directory and copy/set permissions in single layers
COPY entrypoint.sh /entrypoint.sh
COPY entrypoint.sh VERSION /
RUN mkdir -p /socket \
&& chmod +x /entrypoint.sh

143
README.MD
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@@ -2,17 +2,43 @@
A lightweight Docker container that creates a UNIX socket proxy to TCP connections using socat and Alpine Linux.
> [!NOTE]
>_Github repo is a mirror of https://git.djeex.fr/Djeex/socat-proxy. You'll find full package, history and release note there._
## 📑 Table of Contents
- [🚀 Features](#-features)
- [🔧 How It Works](#-how-it-works)
- [📋 Use Case](#-use-case)
- [🛠️ Configuration](#-configuration)
- [Environment Variables](#environment-variables)
- [🚢 Quick Start](#-quick-start)
- [Using Docker Compose (Recommended)](#using-docker-compose-recommended)
- [Using Docker Run](#using-docker-run)
- [💡 Deployment example for Beszel](#-example-secure-docker-socket-access-for-host-mode-containers)
## 🚀 Features
- **Lightweight**: Based on Alpine Linux (~10-15MB image)
- **Configurable**: Environment variable driven configuration
- **Socket Management**: Automatic UNIX socket creation and cleanup
- **Production Ready**: Includes proper error handling and logging
- **Multi-variant**: Standard and minimal Docker images available
## 📋 Use Cases example
## 🔧 How It Works
- Proxy Docker socket from a docker proxy to a container in host mode
1. **Socket Check**: Verifies if UNIX socket exists at startup
2. **Cleanup**: Removes existing socket file/folder if present
3. **Socket Creation**: Creates new UNIX socket using `nc -lU`
4. **Proxy Start**: Starts socat to proxy UNIX socket to TCP endpoint
## 📋 Use Case
Proxy Docker socket from a docker proxy to a container in host mode without directly exposing socket to host. For example:
[Beszel](https://beszel.dev/) is a monitoring tool that requires `network_mode: host` to function properly. This creates a security challenge: Beszel needs access to the Docker socket, but it cannot reach a containerized docker-socket-proxy due to the network isolation. Running docker-socket-proxy in host mode or exposing port to host would also be highly insecure.
**Socat-proxy solves this problem** by creating a secure bridge between host-mode containers and containerized socket proxies. It exposes a UNIX socket file on the host filesystem that Beszel can access, while securely forwarding all Docker API requests to the socket-proxy running on the bridge network.
![](https://git.djeex.fr/Djeex/socat-proxy/raw/branch/main/illustration/socat-proxy.svg)
## 🛠️ Configuration
@@ -22,50 +48,109 @@ A lightweight Docker container that creates a UNIX socket proxy to TCP connectio
|----------|---------|-------------|---------|
| `TARGET_HOST` | - | Target hostname/IP to proxy to | `socket-proxy-beszel` |
| `TARGET_PORT` | - | Target port to proxy to | `2375` |
| `UNIX_SOCKET_PATH` | - | Path to UNIX socket inside container | `/socket/docker.sock` |
| `SOCKET_PATH` | - | Host path for socket mounting | `/your/container/sock/` |
| `UNIX_SOCKET_NAME` | - | Name of the socket file | `docker.sock` |
| `UNIX_SOCKET_PATH` | - | Path to UNIX socket inside container | `/socket` |
| `HOST_SOCKET_PATH` | - | Host path for socket mounting | `/docker/beszel-agent/sock` |
| `DEBUG_LEVEL` | - | Level of logs verbose | `0`,`1`,`2`,`3` |
## 🚢 Quick Start
### Using Docker Compose (Recommended)
1. Clone the repository:
1. Create a `.env` file with your configuration:
```bash
git clone https://git.djeex.fr/Djeex/socat-proxy
cd socat-proxy
TARGET_HOST= #your target host
TARGET_PORT= #your target host port
UNIX_SOCKET_NAME= #your socket file name
UNIX_SOCKET_PATH= #your socket folder path inside socat-proxy
HOST_SOCKET_PATH= #your socket folder path inside your host
DEBUG_LEVEL=1
```
2. Configure environment variables in `.env` file:
```bash
TARGET_HOST= # Target hostname/IP to proxy to
TARGET_PORT= # Target port to proxy to
UNIX_SOCKET_PATH= # Path to UNIX socket inside container
HOST_SOCKET_PATH= # Host path for socket mounting
2. Create a `compose.yml` file:
```yaml
services:
socat-proxy:
image: git.djeex.fr/djeex/socat-proxy:latest
environment:
- TARGET_HOST=${TARGET_HOST}
- TARGET_PORT=${TARGET_PORT}
- UNIX_SOCKET_NAME=${UNIX_SOCKET_NAME}
- UNIX_SOCKET_PATH=${UNIX_SOCKET_PATH}
- HOST_SOCKET_PATH=${HOST_SOCKET_PATH}
- DEBUG_LEVEL=${DEBUG_LEVEL}
volumes:
- ${HOST_SOCKET_PATH}:${UNIX_SOCKET_PATH}
restart: unless-stopped
```
3. Start the service:
```bash
docker-compose up -d
docker compose up -d
```
### Using Docker Run
```bash
docker build -t socat-proxy .
docker run -d \
--name socat-proxy \
-e TARGET_HOST=your-target-host \
-e TARGET_PORT=your-target-port \
-e UNIX_SOCKET_PATH=your-unix-socket-path \
-e HOST_SOCKET_PATH=your-socket-host-path \
-v /your-origin-socket-path:/socket \
socat-proxy
-e TARGET_HOST= #your target host \
-e TARGET_PORT= #your target host port \
-e UNIX_SOCKET_NAME= #your socket file name \
-e UNIX_SOCKET_PATH= #your socket folder path inside socat-proxy \
-e HOST_SOCKET_PATH= #your socket folder path inside your host\
-e DEBUG_LEVEL=1 \
-v ${HOST_SOCKET_PATH}:${UNIX_SOCKET_PATH}$ \
git.djeex.fr/djeex/socat-proxy:latest
```
## 🔧 How It Works
1. **Socket Check**: Verifies if UNIX socket exists at startup
2. **Cleanup**: Removes existing socket file/folder if present
3. **Socket Creation**: Creates new UNIX socket using `nc -lU`
4. **Proxy Start**: Starts socat to proxy UNIX socket to TCP endpoint
## 💡 Deployment example for Beszel
```yaml
services:
socat-proxy:
image: git.djeex.fr/djeex/socat-proxy:latest
container_name: socat-proxy-beszel
environment:
- TARGET_HOST=${TARGET_HOST}
- TARGET_PORT=${TARGET_PORT}
- UNIX_SOCKET_PATH=${UNIX_SOCKET_PATH}
- HOST_SOCKET_PATH=${HOST_SOCKET_PATH}
- UNIX_SOCKET_NAME=${UNIX_SOCKET_NAME}
volumes:
- ${HOST_SOCKET_PATH}:${UNIX_SOCKET_PATH}
restart: unless-stopped
depends_on:
- ${TARGET_HOST}
socket-proxy:
image: lscr.io/linuxserver/socket-proxy:latest
container_name: ${TARGET_HOST}
security_opt:
- no-new-privileges:true
environment:
- CONTAINERS=1
- INFO=1
volumes:
- /var/run/docker.sock:/var/run/docker.sock:ro
restart: unless-stopped
read_only: true
tmpfs:
- /run
beszel-agent:
image: henrygd/beszel-agent:latest
container_name: beszel-agent
restart: unless-stopped
network_mode: host
security_opt:
- no-new-privileges:true
volumes:
- ${HOST_SOCKET_PATH}/${UNIX_SOCKET_NAME}:/var/run/docker.sock:ro
environment:
- #... your Beszel environment var
depends_on:
- socat-proxy
```

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@@ -1 +1 @@
0.1
1.0.0

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@@ -1,21 +1,13 @@
version: '3.8'
---
services:
socat-proxy:
build: .
environment:
- TARGET_HOST=${TARGET_HOST:}
- TARGET_PORT=${TARGET_PORT:}
- TARGET_HOST=${TARGET_HOST}
- TARGET_PORT=${TARGET_PORT}
- UNIX_SOCKET_NAME=${UNIX_SOCKET_NAME}
- UNIX_SOCKET_PATH=${UNIX_SOCKET_PATH}
- HOST_SOCKET_PATH=${HOST_SOCKET_PATH}
volumes:
- ${HOST_SOCKET_PATH:-/tmp/docker-proxy}:/socket
networks:
- proxy-network
- ${HOST_SOCKET_PATH}:${UNIX_SOCKET_PATH}
restart: unless-stopped
volumes:
socket_volume:
networks:
proxy-network:
external: false

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@@ -1,100 +1,145 @@
#!/bin/sh
set -e
# Set default values if not provided
TARGET_HOST=${TARGET_HOST}
TARGET_PORT=${TARGET_PORT}
UNIX_SOCKET_PATH=${UNIX_SOCKET_PATH}
UNIX_SOCKET_NAME=$(basename "$UNIX_SOCKET_PATH")
HOST_SOCKET_PATH=${HOST_SOCKET_PATH}
CYAN="\033[1;36m"
NC="\033[0m"
DEBUG_LEVEL=${DEBUG_LEVEL:-1}
UNIX_SOCKET_PATH=${UNIX_SOCKET_PATH%/}
HOST_SOCKET_PATH=${HOST_SOCKET_PATH%/}
FULL_HOST_SOCKET_PATH="$HOST_SOCKET_PATH/$UNIX_SOCKET_NAME"
FULL_UNIX_SOCKET_PATH="$UNIX_SOCKET_PATH/$UNIX_SOCKET_NAME"
VERSION=$(cat VERSION)
echo -e "${CYAN}╭────────────────────────────────────────────────╮${NC}"
echo -e "${CYAN}${NC} Socat-proxy - Version ${VERSION}${NC} ${CYAN}${NC}"
echo -e "${CYAN}├────────────────────────────────────────────────┤${NC}"
echo -e "${CYAN}${NC} Source: https://git.djeex.fr/Djeex/socat-proxy ${CYAN}${NC}"
echo -e "${CYAN}${NC} Mirror: https://github.com/Djeex/socat-proxy ${CYAN}${NC}"
echo -e "${CYAN}╰────────────────────────────────────────────────╯${NC}"
# Validate required environment variables
if [ -z "$TARGET_HOST" ]; then
echo "ERROR: TARGET_HOST environment variable is required"
echo "[✗] TARGET_HOST environment variable is required"
exit 1
fi
if [ -z "$TARGET_PORT" ]; then
echo "ERROR: TARGET_PORT environment variable is required"
echo "[✗] TARGET_PORT environment variable is required"
exit 1
fi
if [ -z "$UNIX_SOCKET_NAME" ]; then
echo "[✗] UNIX_SOCKET_NAME environment variable is required"
exit 1
fi
if [ -z "$UNIX_SOCKET_PATH" ]; then
echo "ERROR: UNIX_SOCKET_PATH environment variable is required"
echo "[✗] UNIX_SOCKET_PATH environment variable is required"
exit 1
fi
if [ -z "$HOST_SOCKET_PATH" ]; then
echo "ERROR: HOST_SOCKET_PATH environment variable is required"
echo "[✗] HOST_SOCKET_PATH environment variable is required"
exit 1
fi
echo "Starting socat proxy..."
echo "UNIX socket: $UNIX_SOCKET_PATH"
echo "TCP target: $TARGET_HOST:$TARGET_PORT"
echo "HOST path: $HOST_SOCKET_PATH"
echo "Full socket path: $FULL_SOCKET_PATH"
echo "[~] Starting socat proxy..."
echo "[i] TCP target: $TARGET_HOST:$TARGET_PORT"
echo "[i] HOST path: $HOST_SOCKET_PATH"
echo "[i] Full host socket path: $FULL_HOST_SOCKET_PATH"
echo "[i] Full socket path: $FULL_UNIX_SOCKET_PATH"
# Check if socket file/folder exists and handle it
FULL_SOCKET_PATH="$HOST_SOCKET_PATH/$UNIX_SOCKET_NAME"
if [ -e "$FULL_SOCKET_PATH" ]; then
echo "Socket file/folder $FULL_SOCKET_PATH exists, removing it..."
if rm -rf "$FULL_SOCKET_PATH"; then
echo "SUCCESS: Removed existing socket $FULL_SOCKET_PATH"
if [ -e "$FULL_UNIX_SOCKET_PATH" ]; then
echo "[~] Socket file/folder $FULL_UNIX_SOCKET_PATH exists, removing it..."
if rm -rf "$FULL_UNIX_SOCKET_PATH"; then
echo "[✓] Removed existing socket $FULL_UNIX_SOCKET_PATH"
else
echo "ERROR: Failed to remove existing socket $FULL_SOCKET_PATH"
echo "[✗] Failed to remove existing socket $FULL_UNIX_SOCKET_PATH"
exit 1
fi
fi
echo "Creating socket directory structure..."
echo "[~] Creating socket directory structure..."
# Create directory if needed
if mkdir -p "$HOST_SOCKET_PATH"; then
echo "SUCCESS: Created directory $HOST_SOCKET_PATH"
if mkdir -p "$UNIX_SOCKET_PATH"; then
echo "[✓] Created directory $UNIX_SOCKET_PATH"
else
echo "ERROR: Failed to create directory $HOST_SOCKET_PATH"
echo "[✗] Failed to create directory $UNIX_SOCKET_PATH"
exit 1
fi
echo "Creating socket with netcat..."
# Create socket with nc -lU in background and then kill it to create the socket file
if timeout 1 nc -lU "$FULL_SOCKET_PATH" 2>/dev/null || true; then
echo "SUCCESS: Socket created at $FULL_SOCKET_PATH"
echo "[~] Creating socket with netcat..."
# Create socket file by touching it, then remove it (this creates the path but leaves it clean for socat)
touch "$FULL_UNIX_SOCKET_PATH"
rm "$FULL_UNIX_SOCKET_PATH"
echo "[✓] Socket path prepared at $FULL_UNIX_SOCKET_PATH"
# Debug: Check if socket file exists and its permissions
if [ -S "$FULL_UNIX_SOCKET_PATH" ]; then
echo "[✓] Socket file exists and is a socket"
ls -la "$FULL_UNIX_SOCKET_PATH"
else
echo "WARNING: Socket creation with netcat had issues, but continuing..."
echo "[!] Socket file does not exist or is not a socket"
ls -la "$UNIX_SOCKET_PATH"
fi
echo "Testing connection to target..."
echo "[~] Testing connection to target..."
# Test if we can reach the target before starting socat
if ! nc -z "$TARGET_HOST" "$TARGET_PORT" 2>/dev/null; then
echo "WARNING: Cannot connect to $TARGET_HOST:$TARGET_PORT - socat will retry automatically"
echo "[!] Cannot connect to $TARGET_HOST:$TARGET_PORT - socat will retry automatically"
else
echo "SUCCESS: Connection to $TARGET_HOST:$TARGET_PORT is working"
echo "[✓] Connection to $TARGET_HOST:$TARGET_PORT is working"
fi
# Signal handler for graceful shutdown
cleanup() {
echo "Received SIGTERM, shutting down gracefully..."
echo "[!] Received SIGTERM, shutting down gracefully..."
if [ ! -z "$SOCAT_PID" ]; then
echo "Stopping socat process (PID: $SOCAT_PID)..."
echo "[~] Stopping socat process (PID: $SOCAT_PID)..."
kill "$SOCAT_PID" 2>/dev/null || true
wait "$SOCAT_PID" 2>/dev/null || true
fi
echo "Cleanup completed, exiting..."
echo "[~] Cleanup completed, exiting..."
exit 0
}
# Set up signal trap
trap cleanup SIGTERM SIGINT
echo "Starting socat proxy..."
# Start socat with verbose logging and redirect to stdout/stderr
if socat -d -d UNIX-LISTEN:$UNIX_SOCKET_PATH,fork,unlink-early TCP:$TARGET_HOST:$TARGET_PORT & then
echo "[~] Starting socat proxy..."
# Start socat with configurable verbosity
DEBUG_FLAGS=""
if [ "$DEBUG_LEVEL" -eq 1 ]; then
DEBUG_FLAGS="-d"
elif [ "$DEBUG_LEVEL" -eq 2 ]; then
DEBUG_FLAGS="-d -d"
elif [ "$DEBUG_LEVEL" -eq 3 ]; then
DEBUG_FLAGS="-d -d -d"
fi
echo "[i] Using debug level: $DEBUG_LEVEL ($DEBUG_FLAGS)"
if socat $DEBUG_FLAGS UNIX-LISTEN:$FULL_UNIX_SOCKET_PATH,fork,unlink-early TCP:$TARGET_HOST:$TARGET_PORT & then
SOCAT_PID=$!
echo "SUCCESS: Socat started with PID: $SOCAT_PID"
echo "Container is ready and running..."
echo "[✓] Socat started with PID: $SOCAT_PID"
echo "[i] Socat command: socat -d -d UNIX-LISTEN:$FULL_UNIX_SOCKET_PATH,fork,unlink-early TCP:$TARGET_HOST:$TARGET_PORT"
echo "[~] Container is ready and running..."
# Debug: Check socket after socat starts
sleep 2
if [ -S "$FULL_UNIX_SOCKET_PATH" ]; then
echo "[✓] Socat socket is active"
ls -la "$FULL_UNIX_SOCKET_PATH"
else
echo "[!] Socat socket not found"
fi
else
echo "ERROR: Failed to start socat proxy"
echo "[✗] Failed to start socat proxy"
exit 1
fi
@@ -103,6 +148,5 @@ while kill -0 "$SOCAT_PID" 2>/dev/null; do
sleep 1
done
echo "Socat process has stopped"
exit 1
echo "[✗] Socat process has stopped"
exit 1

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