tools-only MCP Reverse Proxy
The MCP Reverse Proxy enables local MCP servers to be accessible through remote gateways without requiring inbound network access. This is similar to SSH reverse tunneling or ngrok, but specifically designed for the MCP protocol.
Overview
The reverse proxy establishes an outbound connection from a local environment to a remote gateway, then tunnels all MCP protocol messages through this persistent connection. This allows:
- Firewall traversal: Share MCP servers without opening inbound ports
- NAT bypass: Work seamlessly behind corporate or home NATs
- Edge deployments: Connect edge servers to central management
- Development testing: Test local servers with cloud-hosted gateways
Architecture
┌─────────────────────┐ ┌──────────────────┐ ┌─────────────┐
│ Local MCP Server │ stdio │ Reverse Proxy │ WS/SSE │ Remote │
│ (uvx mcp-server) │ <-----> │ Client │ <-----> │ Gateway │
└─────────────────────┘ └──────────────────┘ └─────────────┘
↑
│
┌──────┴──────┐
│ MCP Clients │
└─────────────┘
Quick Start
1. Basic Usage
Connect a local MCP server to a remote gateway:
# Set gateway URL and authentication
export REVERSE_PROXY_GATEWAY=https://gateway.example.com
export REVERSE_PROXY_TOKEN=$(python3 -m mcpgateway.utils.create_jwt_token \
--username admin --exp 10080 --secret your-secret-key)
# Run the reverse proxy
python3 -m mcpgateway.reverse_proxy \
--local-stdio "uvx mcp-server-git"
2. Command Line Options
python3 -m mcpgateway.reverse_proxy \
--local-stdio "uvx mcp-server-filesystem --directory /path/to/files" \
--gateway https://gateway.example.com \
--token your-bearer-token \
--reconnect-delay 2 \
--max-retries 10 \
--keepalive 30 \
--log-level DEBUG
Options:
--local-stdio: Command to run the local MCP server (required)--gateway: Remote gateway URL (or use REVERSE_PROXY_GATEWAY env var)--token: Bearer token for authentication (or use REVERSE_PROXY_TOKEN env var)--reconnect-delay: Initial reconnection delay in seconds (default: 1)--max-retries: Maximum reconnection attempts, 0=infinite (default: 0)--keepalive: Heartbeat interval in seconds (default: 30)--log-level: Log level (DEBUG, INFO, WARNING, ERROR, CRITICAL)--verbose: Enable verbose logging (same as --log-level DEBUG)--config: Configuration file (YAML or JSON)
3. Configuration File
Create a reverse-proxy.yaml:
# reverse-proxy.yaml
local_stdio: "uvx mcp-server-git"
gateway: "https://gateway.example.com"
token: "your-bearer-token"
reconnect_delay: 2
max_retries: 0
keepalive: 30
log_level: "INFO"
Run with configuration:
python3 -m mcpgateway.reverse_proxy --config reverse-proxy.yaml
Environment Variables
REVERSE_PROXY_GATEWAY: Remote gateway URLREVERSE_PROXY_TOKEN: Bearer token for authenticationREVERSE_PROXY_RECONNECT_DELAY: Initial reconnection delay (seconds)REVERSE_PROXY_MAX_RETRIES: Maximum reconnection attempts (0=infinite)REVERSE_PROXY_LOG_LEVEL: Python log level
Docker Deployment
Single Container
FROM python:3.11-slim
# Install MCP gateway and server
RUN pip install mcp-gateway mcp-server-git
# Set environment
ENV REVERSE_PROXY_GATEWAY=https://gateway.example.com
ENV REVERSE_PROXY_TOKEN=your-token
# Run reverse proxy
CMD ["python", "-m", "mcpgateway.reverse_proxy", \
"--local-stdio", "mcp-server-git"]
Docker Compose
version: '3.8'
services:
reverse-proxy-git:
image: mcp-gateway:latest
environment:
REVERSE_PROXY_GATEWAY: https://gateway.example.com
REVERSE_PROXY_TOKEN: ${TOKEN}
command: >
python -m mcpgateway.reverse_proxy
--local-stdio "mcp-server-git"
--keepalive 30
--log-level INFO
restart: unless-stopped
reverse-proxy-filesystem:
image: mcp-gateway:latest
environment:
REVERSE_PROXY_GATEWAY: https://gateway.example.com
REVERSE_PROXY_TOKEN: ${TOKEN}
volumes:
- ./data:/data:ro
command: >
python -m mcpgateway.reverse_proxy
--local-stdio "mcp-server-filesystem --directory /data"
restart: unless-stopped
Kubernetes Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: mcp-reverse-proxy
spec:
replicas: 1
selector:
matchLabels:
app: mcp-reverse-proxy
template:
metadata:
labels:
app: mcp-reverse-proxy
spec:
containers:
- name: reverse-proxy
image: mcp-gateway:latest
env:
- name: REVERSE_PROXY_GATEWAY
value: "https://gateway.example.com"
- name: REVERSE_PROXY_TOKEN
valueFrom:
secretKeyRef:
name: mcp-credentials
key: token
command:
- python
- -m
- mcpgateway.reverse_proxy
args:
- --local-stdio
- "mcp-server-git"
- --keepalive
- "30"
resources:
limits:
memory: "256Mi"
cpu: "100m"
Gateway-Side Configuration
The remote gateway must have the reverse proxy endpoints enabled:
1. WebSocket Endpoint
The gateway exposes /reverse-proxy/ws for WebSocket connections:
# Gateway receives connections at:
wss://gateway.example.com/reverse-proxy/ws
2. Session Management
View active reverse proxy sessions:
# List all sessions
curl -H "Authorization: Bearer $TOKEN" \
https://gateway.example.com/reverse-proxy/sessions
# Disconnect a session
curl -X DELETE -H "Authorization: Bearer $TOKEN" \
https://gateway.example.com/reverse-proxy/sessions/{session_id}
3. Virtual Server Registration
Reverse-proxied servers automatically appear in the gateway's server catalog and can be accessed like any other MCP server.
Security Considerations
Authentication
- Always use authentication tokens in production
- Tokens should have appropriate expiration times
- Consider using mutual TLS for additional security
Network Security
- The reverse proxy only requires outbound HTTPS/WSS
- No inbound firewall rules needed
- All traffic is encrypted via TLS
Best Practices
Use specific tokens per deployment
# Generate deployment-specific token python3 -m mcpgateway.utils.create_jwt_token \ --username edge-server-01 \ --exp 10080 \ --secret $JWT_SECRETMonitor connection health
- Check gateway logs for connection events
- Monitor reconnection attempts
- Set up alerts for persistent failures
Resource limits
- Set appropriate memory/CPU limits in containers
- Configure max message sizes
- Implement rate limiting on the gateway
Troubleshooting
Connection Issues
Check connectivity:
# Test gateway reachability curl -I https://gateway.example.com/healthzVerify authentication:
# Test token validity curl -H "Authorization: Bearer $TOKEN" \ https://gateway.example.com/reverse-proxy/sessionsEnable debug logging:
python3 -m mcpgateway.reverse_proxy \ --local-stdio "uvx mcp-server-git" \ --log-level DEBUG
Common Errors
| Error | Cause | Solution |
|---|---|---|
Connection refused |
Gateway unreachable | Check gateway URL and network |
401 Unauthorized |
Invalid token | Regenerate token with correct secret |
WebSocket connection failed |
Firewall blocking WSS | Check outbound port 443 |
Subprocess not running |
Local server crashed | Check server command and logs |
Max retries exceeded |
Persistent network issue | Check network stability |
Performance Tuning
Adjust keepalive interval:
# Shorter interval for unstable networks --keepalive 15 # Longer interval for stable networks --keepalive 60Configure reconnection strategy:
# Quick reconnect with limited retries --reconnect-delay 0.5 --max-retries 20 # Slow reconnect with infinite retries --reconnect-delay 5 --max-retries 0
Advanced Usage
Multiple Local Servers
Run multiple reverse proxies for different servers:
# multi-server.yaml
servers:
- name: git-server
command: "uvx mcp-server-git"
gateway: "https://gateway1.example.com"
- name: filesystem-server
command: "uvx mcp-server-filesystem --directory /data"
gateway: "https://gateway2.example.com"
Load Balancing
Connect the same server to multiple gateways:
# Primary gateway
python3 -m mcpgateway.reverse_proxy \
--local-stdio "uvx mcp-server-git" \
--gateway https://gateway1.example.com &
# Backup gateway
python3 -m mcpgateway.reverse_proxy \
--local-stdio "uvx mcp-server-git" \
--gateway https://gateway2.example.com &
Monitoring Integration
Export metrics for monitoring systems:
# Custom monitoring wrapper
import asyncio
from mcpgateway.reverse_proxy import ReverseProxyClient
class MonitoredReverseProxy(ReverseProxyClient):
async def connect(self):
# Export connection metric
prometheus_client.Counter('reverse_proxy_connections_total').inc()
await super().connect()