feat: initial release - mDNS publisher and resolver for Termux
- mdns-publish.py: publishes movil.local:8022 via Zeroconf - mdns-resolve: raw UDP mDNS resolver (RFC 6762) - ssh-mdns-proxy: SSH ProxyCommand with mDNS/Tailscale/cache fallback - install.sh: automated installer with boot integration Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Andrés Eduardo García Márquez
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__pycache__/
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*.pyc
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# termux-mdns
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mDNS publisher and resolver for Termux (Android).
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Publishes `movil.local` on the local network via Zeroconf so other machines can find the phone by hostname instead of dynamic DHCP IPs.
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## Components
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| Script | Purpose |
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|--------|---------|
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| `mdns-publish.py` | Publishes `movil.local:8022` as an SSH service via mDNS/Zeroconf |
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| `mdns-resolve` | Resolves `.local` hostnames via raw UDP multicast (RFC 6762) |
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| `ssh-mdns-proxy` | SSH ProxyCommand with mDNS → Tailscale → cache fallback chain |
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## Install
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```bash
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pkg install python
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pip install zeroconf
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./install.sh
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```
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## Usage
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From any machine on the LAN:
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```bash
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ssh -p 8022 movil.local
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```
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From the phone to other machines:
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```bash
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ssh dell # resolves via mdns-resolve → ssh-mdns-proxy
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```
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## Boot
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The installer adds `mdns-publish.py` to `~/.termux/boot/start-services` so it starts automatically when Termux boots.
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## License
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MIT
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#!/data/data/com.termux/files/usr/bin/bash
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set -e
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BIN="$HOME/.local/bin"
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BOOT="$HOME/.termux/boot/start-services"
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mkdir -p "$BIN"
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cp mdns-publish.py mdns-resolve ssh-mdns-proxy "$BIN/"
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chmod +x "$BIN/mdns-publish.py" "$BIN/mdns-resolve" "$BIN/ssh-mdns-proxy"
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# Add to boot if not already there
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if ! grep -q "mdns-publish" "$BOOT" 2>/dev/null; then
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sed -i "/^sshd$/a \\\n# Iniciar mDNS (publica movil.local)\nnohup python ~/.local/bin/mdns-publish.py > /dev/null 2>&1 &" "$BOOT"
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echo "Added mdns-publish to boot script"
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fi
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# Start if not running
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if ! pgrep -f mdns-publish.py > /dev/null; then
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nohup python "$BIN/mdns-publish.py" > /dev/null 2>&1 &
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echo "mdns-publish started (PID: $!)"
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else
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echo "mdns-publish already running"
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fi
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echo "Install complete"
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#!/data/data/com.termux/files/usr/bin/python
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"""Publica el servicio SSH como movil.local via mDNS/Zeroconf"""
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import socket
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import signal
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import sys
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from zeroconf import ServiceInfo, Zeroconf, IPVersion
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def get_local_ip():
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"""Obtiene la IP local del dispositivo"""
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try:
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s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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s.connect(('8.8.8.8', 80))
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ip = s.getsockname()[0]
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s.close()
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return ip
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except:
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return '127.0.0.1'
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def main():
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hostname = 'movil'
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port = 8022
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ip = get_local_ip()
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zc = Zeroconf(ip_version=IPVersion.V4Only)
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# Registrar servicio SSH
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info = ServiceInfo(
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'_ssh._tcp.local.',
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f'{hostname}._ssh._tcp.local.',
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addresses=[socket.inet_aton(ip)],
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port=port,
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properties={'description': 'Termux SSH'},
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server=f'{hostname}.local.',
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)
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print(f'Publicando {hostname}.local -> {ip}:{port}')
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zc.register_service(info)
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def signal_handler(sig, frame):
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print('Deteniendo mDNS...')
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zc.unregister_service(info)
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zc.close()
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sys.exit(0)
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signal.signal(signal.SIGINT, signal_handler)
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signal.signal(signal.SIGTERM, signal_handler)
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# Mantener corriendo
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try:
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signal.pause()
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except:
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while True:
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import time
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time.sleep(3600)
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if __name__ == '__main__':
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main()
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#!/data/data/com.termux/files/usr/bin/python3
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"""
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Resuelve hostname.local via mDNS multicast.
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Uso: mdns-resolve <hostname.local>
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Retorna: IP address o exit 1
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"""
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import sys
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import socket
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import struct
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import select
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def build_mdns_query(hostname: str) -> bytes:
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"""Construye query DNS para hostname."""
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# Header: ID=0, Flags=0, QDCOUNT=1, ANCOUNT=0, NSCOUNT=0, ARCOUNT=0
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header = struct.pack('>HHHHHH', 0, 0, 1, 0, 0, 0)
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# Question section
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question = b''
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for part in hostname.rstrip('.').split('.'):
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question += bytes([len(part)]) + part.encode()
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question += b'\x00' # End of name
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question += struct.pack('>HH', 1, 1) # Type A, Class IN
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return header + question
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def parse_mdns_response(data: bytes, hostname: str) -> str | None:
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"""Parsea respuesta mDNS y extrae IP."""
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if len(data) < 12:
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return None
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# Skip header, find answers
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qdcount = struct.unpack('>H', data[4:6])[0]
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ancount = struct.unpack('>H', data[6:8])[0]
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if ancount == 0:
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return None
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# Skip questions
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offset = 12
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for _ in range(qdcount):
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while offset < len(data) and data[offset] != 0:
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if data[offset] & 0xc0 == 0xc0: # Compression
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offset += 2
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break
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offset += data[offset] + 1
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else:
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offset += 1
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offset += 4 # Type + Class
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# Parse answers
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for _ in range(ancount):
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# Skip name (handle compression)
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while offset < len(data):
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if data[offset] & 0xc0 == 0xc0:
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offset += 2
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break
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elif data[offset] == 0:
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offset += 1
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break
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else:
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offset += data[offset] + 1
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if offset + 10 > len(data):
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break
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rtype, rclass, ttl, rdlength = struct.unpack('>HHIH', data[offset:offset+10])
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offset += 10
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# Type A (1) = IPv4 address
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if rtype == 1 and rdlength == 4 and offset + 4 <= len(data):
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ip = socket.inet_ntoa(data[offset:offset+4])
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return ip
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offset += rdlength
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return None
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def resolve_mdns(hostname: str, timeout: float = 2.0) -> str | None:
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"""Resuelve hostname via mDNS multicast."""
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if not hostname.endswith('.local'):
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hostname += '.local'
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MDNS_ADDR = '224.0.0.251'
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MDNS_PORT = 5353
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try:
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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sock.setblocking(False)
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# Enviar query
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query = build_mdns_query(hostname)
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sock.sendto(query, (MDNS_ADDR, MDNS_PORT))
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# Esperar respuesta
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end_time = __import__('time').time() + timeout
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while __import__('time').time() < end_time:
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ready, _, _ = select.select([sock], [], [], 0.1)
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if ready:
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try:
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data, addr = sock.recvfrom(4096)
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ip = parse_mdns_response(data, hostname)
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if ip:
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sock.close()
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return ip
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except:
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pass
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sock.close()
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except Exception as e:
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pass
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return None
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def main():
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if len(sys.argv) < 2:
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print("Uso: mdns-resolve <hostname.local>", file=sys.stderr)
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sys.exit(1)
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hostname = sys.argv[1]
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timeout = float(sys.argv[2]) if len(sys.argv) > 2 else 2.0
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ip = resolve_mdns(hostname, timeout)
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if ip:
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print(ip)
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sys.exit(0)
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else:
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sys.exit(1)
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if __name__ == "__main__":
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main()
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#\!/data/data/com.termux/files/usr/bin/bash
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# ssh-mdns-proxy: Resolve .local via mDNS with fallbacks, then connect
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HOST="$1"
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PORT="${2:-22}"
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CACHE="$HOME/.ssh/mdns-cache"
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QUERY="${HOST%.local}"
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# Alias mapping (short name → mDNS hostname)
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declare -A ALIASES=(
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[dell]="dell-latitude3400"
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[lenovo]="lenovo-ideapad"
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)
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[[ -n "${ALIASES[$QUERY]}" ]] && QUERY="${ALIASES[$QUERY]}"
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# 1. mDNS resolution
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IP=$("$HOME/.local/bin/mdns-resolve" "${QUERY}.local" 2 2>/dev/null)
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# 2. Fallback: Tailscale DNS
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if [[ -z "$IP" ]]; then
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IP=$(getent hosts "${QUERY}.tailb0bb74.ts.net" 2>/dev/null | awk "{print \$1}")
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fi
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# 3. Fallback: cached IP
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if [[ -z "$IP" && -f "$CACHE" ]]; then
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IP=$(grep "^${QUERY} " "$CACHE" 2>/dev/null | awk "{print \$2}")
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fi
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if [[ -z "$IP" ]]; then
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echo "Error: cannot resolve ${HOST}" >&2
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exit 1
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fi
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# Save to cache
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mkdir -p "$(dirname "$CACHE")"
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grep -v "^${QUERY} " "$CACHE" > "${CACHE}.tmp" 2>/dev/null || true
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echo "${QUERY} ${IP}" >> "${CACHE}.tmp"
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mv "${CACHE}.tmp" "$CACHE"
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exec nc "$IP" "$PORT"
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