mtg/contrib/sni-router

SNI-routing deployment for mtg

A turnkey docker compose setup that puts an SNI-aware TCP router (HAProxy) in front of mtg and a real web server (Caddy with automatic HTTPS).

Why

Modern DPI systems actively probe suspected proxies. If the server closes the connection or returns something unexpected, the IP gets flagged. With this setup:

• Telegram clients connect to port 443, HAProxy sees the configured SNI and routes them to mtg (FakeTLS).
• Everything else (browsers, DPI probes, scanners) is routed to Caddy, which responds with a real Let’s Encrypt certificate and serves genuine web content.

Because your domain’s DNS points to this server, the SNI/IP match is natural and passive DPI has nothing to flag.

Quick start

# 1. Point your domain's DNS A/AAAA record to this server's IP.

# 2. Generate an mtg secret:
docker run --rm nineseconds/mtg:2 generate-secret --hex YOUR_DOMAIN

# 3. Edit the config files:
#    - mtg-config.toml  →  paste the secret
#    - haproxy.cfg       →  replace "example.com" in the SNI ACL
#    - .env or export    →  DOMAIN=your.domain

# 4. (Optional) put your site content into www/

# 5. Start:
docker compose up -d

# 6. Verify:
#    - Open https://YOUR_DOMAIN in a browser → you should see the web page
#    - Configure Telegram with the proxy link from:
docker compose exec mtg mtg access /config/config.toml

Real client IPs (PROXY protocol)

HAProxy forwards TCP connections to mtg and Caddy with a PROXY protocol v2 header so both backends see the real client IP instead of HAProxy’s container address. The three pieces must stay in sync:

• haproxy.cfg — send-proxy-v2 on the mtg and web backend server lines
• mtg-config.toml — proxy-protocol-listener = true
• Caddyfile — listener_wrappers { proxy_protocol { ... } tls } on :8443

If you disable one, disable all three, otherwise the backend will fail to parse the connection.

ACME (Let’s Encrypt) notes

HAProxy passes /.well-known/acme-challenge/ requests on :80 to Caddy so that HTTP-01 validation works out of the box. Make sure your domain’s DNS A/AAAA record points to this server before starting.

Architecture

              ┌──────────────────┐
 :443  ──────>│    HAProxy       │
              │  (TCP, SNI peek) │
              └──┬───────────┬───┘
    SNI match    │           │  default
                 v           v
           ┌─────────┐  ┌─────────┐
           │   mtg    │  │  Caddy  │
           │ :3128    │  │ :8443   │
           │ FakeTLS  │  │ real TLS│
           └─────────┘  └─────────┘

Files

File	Purpose
docker-compose.yml	Service definitions
haproxy.cfg	SNI routing rules — edit the domain
mtg-config.toml	mtg proxy config — paste your secret
Caddyfile	Web server config (auto-HTTPS)
www/	Static site content served by Caddy