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switch-lan-play

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Make you and your friends play games like in a LAN.

                     Internet
                        |
                  [SOCKS5 Proxy] (optional)
                        |
        ARP,IPv4        |          LAN Packets
Switch <-------->  PC(lan-play)  <-------------> Server
                                       UDP

NOTE:

  • This project is in an early stage. The protocol may change frequently.

Usage

To play with your friends, you and your friends should run lan-play client connecting to the same Server on your PC, and set static IP on your Switch.

Your PC and Switch must be connected to the same router.

1. Windows Client

  1. Download and run latest Npcap installer.

  2. Must check Installed in WinPcap API-compatible mode. in Npcap installation wizard.

  3. Download the latest lan-play.exe from releases

  4. Run lan-play.exe

After that, you will prompted to enter a server as shown below:

--relay-server-addr is required
Input the relay server address [ domain/ip:port ]:

You can find a list with public servers here: https://www.lan-play.com/

Optionally you can go to the Switch Lan Play Discord to find people to match make: https://discord.gg/zEMCu5n

2. Switch

  1. Make sure lan-play client is running.

  2. Go to your Switch settings page, set the IP address to static. The IP address can be any from 10.13.0.1 to 10.13.255.254, excepting 10.13.37.1. But don't use the same IP address with your friend.

    IP Address 10.13.?.?
    Subnet Mask 255.255.0.0
    Gateway 10.13.37.1
  3. Click save. Your Switch now can access the Internet via your PC.

  4. Launch your game, hold L+R+LStick to enter lan-play mode. Host or join a game, enjoy!

SOCKS5 Proxy

lan-play --socks5-server-addr example.com:1080

Data sent to the relay server does not pass through the proxy.

Build

Debug or Release

cmake -DCMAKE_BUILD_TYPE=Debug .. cmake -DCMAKE_BUILD_TYPE=Release ..

Ubuntu / Debian

This project depends on libpcap, you can install libpcap0.8-dev on Ubuntu or Debian:

sudo apt install libpcap0.8-dev git gcc g++ cmake

Prepare a cmake, gcc, and run like this:

mkdir build
cd build
cmake ..
make

Windows

Use MSYS2 to compile.

pacman -Sy
pacman -S make \
    mingw-w64-x86_64-cmake \
    mingw-w64-x86_64-gcc

To compile 32bit program:

pacman -S mingw-w64-i686-cmake \
    mingw-w64-i686-gcc

Open MSYS2 MinGW 64-bit or MSYS2 MinGW 32-bit.

mkdir build
cd build
cmake -G "MSYS Makefiles" ..
make

Mac OS

brew install cmake
mkdir build
cd build
cmake ..
make

Server

Docker

docker run -d -p 11451:11451/udp -p 11451:11451/tcp spacemeowx2/switch-lan-play

Node

git clone https://github.com/spacemeowx2/switch-lan-play
cd switch-lan-play/server
npm install
npm run build # build ts to js. run it again when code changed.
npm start

Use --port pass the port parameter, or else it will use 11451/udp as default.

Use --simpleAuth pass the auth via username and password, or else there's no authentication.

Use --httpAuth pass the auth via http url, or else there's no authentication.

Use --jsonAuth pass the auth via json file, or else there's no authentication.

Example:

npm run build
npm start -- --port 10086 --simpleAuth username:password

Meanwhile the monitor service will be started on port 11451/tcp by default, you can get online client count via HTTP request:

Request: GET http://{YOUR_SERVER_IP}:11451/info

Response: { "online": 42 }

Protocol

The protocol is very simple now, but I'm going to add some fileds to calculate network quality(packet loss, ping), like timestamp, seq_id, etc.

struct packet {
    uint8_t type;
    uint8_t payload[packet_len - 1];
};
enum type {
    KEEPALIVE = 0,
    IPV4 = 1,
    PING = 2,
    IPV4_FRAG = 3
};

The server can read IP addresses from payload and save source IP -> LAN IP to a cache table. If target ip address shown in payload doesn't hit the cache, broadcast this packet to the entire room(now a server is a room).