tsunagi/README.md

tsunagi

A mesh VPN with no server.
Pick a network name, share a secret, and your machines are on one private network.

laptop$ tsng join -n home
joined `home`
  secret  tsn1u7c…

server$ tsng join -n home -s tsn1u7c…
server$ tsng id hostname server

laptop$ ssh server.home

No account, no coordination server, no admin console, no keys to approve. Anyone who knows the name and the secret is in. Nobody else can find the network, let alone enter it.

Why

Tailscale, Headscale and ZeroTier are great, but each needs a control server: theirs, or one you have to run and keep alive. tsunagi doesn't. Machines find each other through the public BitTorrent DHT, connect directly (hole punching, with relay fallback), and keep the network state among themselves.

	Tailscale	Headscale	ZeroTier	tsunagi
Control server	hosted by vendor	you run it	hosted or self-run	none
Account / sign-in	yes	yes	yes	no
To join a network	sign in, get approved	pre-auth key	network ID, approval	name + secret
Direct connections	yes	yes	yes	yes
Exit nodes	yes	yes	via routes	yes

Features

• Two things to know: a network name and a secret. A secret is generated for you when you make a network.
• Direct, encrypted links between members (WireGuard cryptography), with relay fallback behind strict NATs.
• Names for machines: server.home just works, even while server is switched off. A name belongs to whoever claimed it first; a later device with the same name keeps working by address and is told so.
• Exit nodes: send all your internet traffic through any member that offers one.
• Multi-hop: members that can't reach each other directly are routed through a member that can, over whatever kind of link each hop has. A member reached that way is online, and shown as relayed; traffic moves to a direct link by itself the moment one comes up.
• LAN games: UDP broadcasts are relayed, so "LAN" lobbies show up across the mesh.
• Several networks at once on one device.
• Tray app for Windows, macOS and Linux; a command line for everything.

Install

Grab a build from the latest release.

Platform	How
Windows	Run tsunagi-setup-<version>-x86_64.exe. Installs the service, the tray and tsng.
macOS	brew tap house-of-vanity/tap && brew install --cask tsunagi-gui CLI only: brew install tsunagi
Debian / Ubuntu	sudo apt install ./tsunagi-gui_<version>_amd64.deb (tsunagi_… for no tray)
Arch	sudo pacman -U tsunagi-gui-<version>-1-x86_64.pkg.tar.zst
NixOS	Flake and module below
Any other Linux	Unpack the tarball, then sudo ./install.sh && sudo systemctl enable --now tsunagi

Linux packages run the agent as an unprivileged service user. Add yourself to the tsunagi group (sudo usermod -aG tsunagi $USER, then log in again) to use tsng and the tray without sudo.

Quick start

tsng join -n home                 # first machine: makes the network and prints a secret
tsng join -n home -s tsn1…        # every other machine
tsng status                       # who is online, over which path

Every member gets an address in 10.13.37.0/24 and a name like <host>.home. Machines are called tsunagi-<id> until you rename them: tsng id hostname laptop.

Exit nodes

tsng network exit-node home on    # on the machine that should be the exit
tsng exit-node                    # on another one: who offers an exit
tsng exit-node laptop             # send everything through it
tsng exit-node off

The tray does the same with a checkbox. An exit node sees everything you send through it, so use only members you trust. Details and per-OS notes.

Platforms

Platform	Build	CLI tsng	Tray	Exit node: offer / use	Packages
Linux x86_64	release	✔	✔	✔ / ✔	.deb, .pkg.tar.zst, tarball, Nix
Linux aarch64	release	✔	–¹	✔ / ✔	.deb, .pkg.tar.zst, tarball, Nix
Linux armv7	release	✔	–¹	✔ / ✔	.deb, .pkg.tar.zst, tarball
macOS, Apple silicon	release	✔	✔	✔ / ✔²	Homebrew, tarball
macOS, Intel	from source	✔³	✔³	✔ / ✔²³	–
Windows x86_64	release	✔	✔	✔ / ✔²	installer, zip

^{¹ Not in the release; builds from source (and through Nix). ² Newer and less battle-tested than on Linux. ³ Builds from source, not covered by CI.}

The Linux CLI is a single static binary: it runs on any distribution.

NixOS

The repository is a flake with a package and a module.

# flake.nix
{
  inputs.tsunagi.url = "github:house-of-vanity/tsunagi";

  outputs = { nixpkgs, tsunagi, ... }: {
    nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
      modules = [
        tsunagi.nixosModules.default
        {
          services.tsunagi = {
            enable = true;
            tray.enable = true;      # optional, for desktops
            users = [ "alice" ];     # may use tsng and the tray without sudo
          };
        }
      ];
    };
  };
}

Just trying it: nix run github:house-of-vanity/tsunagi#tsunagi-cli -- --help. packages.<system>.tsunagi (with the tray) and tsunagi-cli are also exported, along with overlays.default.

Build from source

Rust 1.91 or newer.

cargo build --release --bin tsng               # the agent and CLI
cargo build --release --bin tsunagi-tray       # the tray (Linux needs GTK 3 and libayatana-appindicator)

Windows needs Wintun next to tsng.exe. Per-platform notes: Linux, Arch, macOS, Windows.

How it works

• Your name and secret derive a network identity. Members publish signed contact records to the public Mainline DHT under it, and find each other there.
• Every connection proves knowledge of the secret before it's accepted. Traffic between members is end-to-end encrypted, relays included.
• Addresses and names are claimed with each device's own key and replicated between members. There is no one in charge, so nothing to be taken down.

The secret is the only key, so make it a good one (the generated ones are). The threat model says what this does and doesn't protect against.

Documentation

Architecture · Protocol · WireGuard data plane · Routing · Exit nodes · Threat model · Contributing

Licence

WTFPL: do what the fuck you want to.