┌─────────────┐      ┌─────────────┐      ┌─────────────┐      ┌──────────────┐
│ Application │─────▶│   Client    │─────▶│   Server    │─────▶│  Internet    │
│  (Browser)  │ TCP  │ SOCKS5:1080 │ SMTP │  Port 587   │ TCP  │              │
│             │◀─────│             │◀─────│             │◀─────│              │
└─────────────┘      └─────────────┘      └─────────────┘      └──────────────┘
                            │                    │
                            │   Looks like       │
                            │   Email Traffic    │
                            ▼                    ▼
                     ┌────────────────────────────────┐
                     │     DPI Firewall               │
                     │  ✅ Sees: Normal SMTP Session  │
                     │  ❌ Cannot see: Tunnel Data    │
                     └────────────────────────────────┘

curl -sSL https://raw.githubusercontent.com/x011/smtp-tunnel-proxy/main/install.sh | sudo bash

smtp-tunnel-adduser bob      # Add user + generate client ZIP
smtp-tunnel-listusers        # List all users
smtp-tunnel-deluser bob      # Remove a user

smtp-tunnel-update           # Updates code, preserves config/certs/users

SMTP Tunnel Proxy Client
User: alice

[INFO] Starting SMTP Tunnel...
[INFO] SOCKS5 proxy will be available at 127.0.0.1:1080

Connecting to myserver.duckdns.org:587
Connected - binary mode active
SOCKS5 proxy on 127.0.0.1:1080

cd alice
pip install -r requirements.txt
python client.py

# Download files
scp [email protected]:/etc/smtp-tunnel/ca.crt .

# Create config.yaml:
cat > config.yaml << EOF
client:
  server_host: "myserver.duckdns.org"
  server_port: 587
  socks_port: 1080
  username: "alice"
  secret: "your-secret-from-admin"
  ca_cert: "ca.crt"
EOF

# Run client
python client.py -c config.yaml

export ALL_PROXY=socks5://127.0.0.1:1080

# curl
curl -x socks5h://127.0.0.1:1080 https://ifconfig.me

# git
git config --global http.proxy socks5://127.0.0.1:1080

# Environment variable
export ALL_PROXY=socks5://127.0.0.1:1080

# Should show your VPS IP
curl -x socks5://127.0.0.1:1080 https://ifconfig.me

users:
  alice:
    secret: "auto-generated-secret"
    # whitelist:              # Optional: restrict to specific IPs
    #   - "192.168.1.100"
    #   - "10.0.0.0/8"        # CIDR notation supported
    # logging: true           # Optional: disable to stop logging this user

  bob:
    secret: "another-secret"
    whitelist:
      - "203.0.113.50"        # Bob can only connect from this IP
    logging: false            # Don't log Bob's activity

# Check status
sudo systemctl status smtp-tunnel

# Restart after config changes
sudo systemctl restart smtp-tunnel

# View logs
sudo journalctl -u smtp-tunnel -n 100

# Uninstall
sudo /opt/smtp-tunnel/uninstall.sh

python server.py [-c CONFIG] [-d]

  -c, --config    Config file (default: config.yaml)
  -d, --debug     Enable debug logging

python client.py [-c CONFIG] [--server HOST] [--server-port PORT]
                 [-p SOCKS_PORT] [-u USERNAME] [-s SECRET] [--ca-cert FILE] [-d]

  -c, --config      Config file (default: config.yaml)
  --server          Override server domain
  --server-port     Override server port
  -p, --socks-port  Override local SOCKS port
  -u, --username    Your username
  -s, --secret      Override secret
  --ca-cert         CA certificate path
  -d, --debug       Enable debug logging

smtp-tunnel-adduser <username> [-u USERS_FILE] [-c CONFIG] [--no-zip]
    Add a new user and generate client package

smtp-tunnel-deluser <username> [-u USERS_FILE] [-f]
    Remove a user (use -f to skip confirmation)

smtp-tunnel-listusers [-u USERS_FILE] [-v]
    List all users (use -v for detailed info)

smtp-tunnel-update
    Update server to latest version (preserves config/certs/users)

smtp_proxy/
├── 📄 server.py               # Server (runs on VPS)
├── 📄 client.py               # Client (runs locally)
├── 📄 common.py               # Shared utilities
├── 📄 generate_certs.py       # Certificate generator
├── 📄 config.yaml             # Server/client configuration
├── 📄 users.yaml              # User database
├── 📄 requirements.txt        # Python dependencies
├── 📄 install.sh              # One-liner server installer
├── 📄 smtp-tunnel.service     # Systemd unit file
├── 🔧 smtp-tunnel-adduser     # Add user script
├── 🔧 smtp-tunnel-deluser     # Remove user script
├── 🔧 smtp-tunnel-listusers   # List users script
├── 🔧 smtp-tunnel-update      # Update server script
├── 📄 README.md               # This file
└── 📄 TECHNICAL.md            # Technical documentation

/opt/smtp-tunnel/              # Application files
/etc/smtp-tunnel/              # Configuration files
  ├── config.yaml
  ├── users.yaml
  ├── server.crt
  ├── server.key
  └── ca.crt
/usr/local/bin/                # Management commands
  ├── smtp-tunnel-adduser
  ├── smtp-tunnel-deluser
  ├── smtp-tunnel-listusers
  └── smtp-tunnel-update

# Enable detailed logging
python server.py -d
python client.py -d

# View systemd logs
journalctl -u smtp-tunnel -f