Show HN: SMTP Tunnel – A SOCKS5 proxy disguised as email traffic to bypass DPI
lobito25 Wednesday, January 07, 2026
A fast SOCKS5 proxy that tunnels your traffic through what looks like normal SMTP email, bypassing Deep Packet Inspection firewalls.
How it works: - Client runs a local SOCKS5 proxy (127.0.0.1:1080) - Traffic is sent to server disguised as SMTP (EHLO, STARTTLS, AUTH) - DPI sees legitimate email session, not a VPN/proxy
Features: - One-liner install on any Linux VPS - Multi-user with per-user secrets and IP whitelists - Auto-generated client packages (just double-click to run) - Auto-reconnect on connection loss - Works with any app that supports SOCKS5
Tech: Python/asyncio, TLS 1.2+, HMAC-SHA256 auth
GitHub: https://github.com/x011/smtp-tunnel-proxy
Summary
This article describes an SMTP tunnel proxy, a tool that allows users to bypass censorship and access blocked email services by tunneling SMTP traffic through an open port. The proxy provides a secure and anonymous way to send and receive emails, making it useful for individuals in countries with strict internet censorship.
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