mtg/contrib/sni-router/README.md

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

ACME (Let’s Encrypt) notes

Caddy needs to answer the ACME HTTP-01 challenge on port 80. The default haproxy.cfg redirects all :80 traffic to HTTPS. If Caddy cannot obtain a certificate, either:

1. Temporarily stop HAProxy, let Caddy bind :80 directly for the initial certificate, then start the full stack; or
2. Use DNS-01 validation in the Caddyfile (requires a DNS provider plugin); or
3. Add an HAProxy ACL that passes /.well-known/acme-challenge/ requests to the Caddy backend instead of redirecting.

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