utility-scripts/lanshare
Claude cc57356a53
Fix ICE failures by replacing mDNS .local addresses with real peer IPs
Modern browsers obfuscate local IP addresses with mDNS hostnames
(e.g. abcdef12-3456.local) for privacy. When mDNS resolution is
unavailable on the LAN, WebRTC ICE candidates cannot be resolved
and the peer connection fails.

This fix makes the signaling server extract each client's real IP
from the TCP connection and share it via Welcome/PeerJoined messages.
The client then replaces any .local mDNS addresses in SDP offers,
answers, and trickle ICE candidates with the peer's actual IP address,
enabling direct IP connectivity without relying on mDNS.

https://claude.ai/code/session_01EZrFdyAR35RLwRdHUA9zPJ
2026-02-09 07:38:49 +00:00
..
src Fix ICE failures by replacing mDNS .local addresses with real peer IPs 2026-02-09 07:38:49 +00:00
static Fix ICE failures by replacing mDNS .local addresses with real peer IPs 2026-02-09 07:38:49 +00:00
.gitignore Add local screenshare app 2026-02-04 12:18:48 +01:00
Cargo.lock Add local screenshare app 2026-02-04 12:18:48 +01:00
Cargo.toml Add local screenshare app 2026-02-04 12:18:48 +01:00
lanshare.crt Add local screenshare app 2026-02-04 12:18:48 +01:00
lanshare.key Add local screenshare app 2026-02-04 12:18:48 +01:00
README.md Update 2026-02-09 08:22:15 +01:00

LAN Share

A peer-to-peer screen sharing application for local networks. No accounts, no cloud services — just open a browser and share.

Features

  • WebRTC P2P: Direct peer-to-peer connections, video never touches the server
  • Audio support: Optionally share system audio with your screen
  • Multiple streams: View multiple shared screens, select which one to focus on
  • Zero config: Just run the server and open the URL in any browser
  • Keyboard shortcuts: F for fullscreen, M for mute, Escape to expand sidebar

Building

cargo build --release

The binary will be at target/release/lanshare.

Running

./target/release/lanshare

Or with cargo:

cargo run --release

The server starts on http://0.0.0.0:8080 by default.

CLI Options

Usage: lanshare [OPTIONS]

Options:
  -H, --host <IP>    IP address to bind to [default: 0.0.0.0]
  -p, --port <PORT>  Port to listen on [default: 8080]
  -v, --verbose      Enable verbose/debug logging
  -q, --quiet        Quiet mode - only show errors
  -h, --help         Print help
  -V, --version      Print version

Examples:

# Listen on a specific interface
lanshare --host 192.168.1.100 --port 3000

# Localhost only (for testing)
lanshare -H 127.0.0.1

# Quiet mode
lanshare -q

CLI Options

LAN Share - Peer-to-peer screen sharing for local networks

Usage: lanshare [OPTIONS]

Options:
  -H, --host <HOST>  Host address to bind to [default: 0.0.0.0]
  -p, --port <PORT>  Port to listen on [default: 8080]
  -v, --verbose      Enable verbose logging
  -h, --help         Print help
  -V, --version      Print version

Examples

# Run on default settings (0.0.0.0:8080)
lanshare

# Run on a specific port
lanshare -p 3000

# Bind to localhost only
lanshare -H 127.0.0.1 -p 8080

# Run with verbose logging
lanshare -v

Usage

  1. Start the server on any machine in your LAN
  2. Open http://<server-ip>:8080 in a browser on each device
  3. Enter your name when prompted
  4. Click "Start Sharing" to share your screen
  5. Select shared screens from the sidebar to view them

Architecture

┌─────────────────────────────────────────────────────────────┐
│                      Signaling Server                        │
│                    (Rust/Axum/WebSocket)                     │
│  - Peer discovery                                            │
│  - Relays SDP offers/answers (with bundled candidates)       │
└─────────────────────────────────────────────────────────────┘
           │                                    │
           │ WebSocket                          │ WebSocket
           │ (signaling only)                   │ (signaling only)
           ▼                                    ▼
    ┌─────────────┐                      ┌─────────────┐
    │   Peer A    │◄────────────────────►│   Peer B    │
    │  (Browser)  │     Direct WebRTC    │  (Browser)  │
    └─────────────┘   (video/audio)      └─────────────┘

100% Local Network — No external services, simple direct connections:

  • No STUN/TURN servers needed
  • No trickle ICE — candidates bundled directly in SDP
  • One offer + one answer = connected
  • Video/audio streams stay entirely on your LAN

Browser Support

Tested on:

  • Chrome/Chromium
  • Firefox
  • Edge
  • Safari (macOS)

Note: Screen sharing with audio requires Chrome/Edge on Windows/macOS. Firefox and Linux may have limited audio capture support depending on the system.

Configuration

Command-line options take precedence over defaults. See lanshare --help for all options.

Environment variables:

  • RUST_LOG: Override log level (e.g., RUST_LOG=lanshare=debug)

Security Notes

  • This is designed for trusted local networks only
  • No authentication — anyone with the URL can join
  • No encryption beyond what WebRTC provides by default (DTLS-SRTP)
  • Don't expose to the internet without additional security measures

License

MIT