termux-mdns/README.md

termux-mdns

mDNS publisher and resolver for Termux (Android).

Problem

Android phones get dynamic IPs via DHCP. Every time the phone reconnects to WiFi, the IP changes. This makes SSH connections unreliable since you'd need to find the new IP each time.

Solution

This project publishes movil.local on the local network via Zeroconf (mDNS), so any machine on the LAN can find the phone by hostname regardless of its current IP.

It also includes a resolver and SSH proxy so the phone can find other .local machines on the network.

Components

Script	What it does
mdns-publish.py	Publishes movil.local:8022 as an SSH service via mDNS multicast
mdns-resolve	Resolves .local hostnames via raw UDP multicast (RFC 6762)
ssh-mdns-proxy	SSH ProxyCommand with fallback chain: mDNS → Tailscale DNS → local cache

Requirements

• Termux with Termux:Boot (for auto-start)
• Python 3
• zeroconf Python package
• sshd running in Termux (default port 8022)

Install

pkg install python openssh
pip install zeroconf
git clone https://github.com/andresgarcia0313/termux-mdns.git
cd termux-mdns
./install.sh

The installer copies scripts to ~/.local/bin/, adds mdns-publish.py to ~/.termux/boot/start-services, and starts the service immediately.

Usage

From another machine → phone

# Direct (any machine with mDNS/avahi support)
ssh -p 8022 user@movil.local

# Or add to ~/.ssh/config:
Host phone
    HostName movil.local
    Port 8022
    User u0_a260

From the phone → other machines

# Uses ssh-mdns-proxy as ProxyCommand
ssh dell          # resolves dell-latitude3400.local via mDNS
ssh lenovo        # resolves lenovo-ideapad.local via mDNS

To use the proxy, add this to your ~/.ssh/config on the phone:

Host dell lenovo
    ProxyCommand ~/.local/bin/ssh-mdns-proxy %h %p

How it works

1. Publishing: mdns-publish.py uses the zeroconf library to register an _ssh._tcp service on the mDNS multicast group (224.0.0.251:5353). Any device on the LAN with mDNS support (Linux/avahi, macOS/Bonjour, Windows) can resolve movil.local.

2. Resolving: mdns-resolve sends raw UDP queries to the mDNS multicast address and parses A record responses. This works without needing avahi (which isn't available in Termux).

3. SSH proxy: ssh-mdns-proxy chains three resolution methods — mDNS first, then Tailscale DNS, then a local IP cache — so SSH connections work across different network conditions.

License

MIT