# baalvpn

A hub-and-spoke VPN for IPv6

## Features
* **Post-quantum security:** Uses [HPKE](https://datatracker.ietf.org/doc/html/rfc9180/)([XWingMLKEM768X25519](https://datatracker.ietf.org/doc/html/draft-connolly-cfrg-xwing-kem/), [HKDF-SHA-256](https://en.wikipedia.org/wiki/HKDF)) + [XChaCha20-Poly1305](https://en.wikipedia.org/wiki/ChaCha20-Poly1305#XChaCha20-Poly1305_%E2%80%93_extended_nonce_variant) for encryption and [ML-DSA-44](https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.204.pdf) for signatures.
* **NAT-resistant architecture:** Any device with Internet access can easily join the network.
* **Cross-platform:** Tested on Linux, Windows and macOS.

## Protocol

See [proto.go](https://git.ton1.dev/toni/baalvpn/src/branch/main/shared/proto.go) for details

### Known limitations
* A compromised server could give out fake pubkeys allowing a MITM attack and decrypting the peer-to-peer traffic
* The keys are rotated only on client and server restart
* The protocol is vulnerable to replay attacks

## Setup

### Prerequisites
* [Go](https://go.dev/dl/) 1.26.3+

### Building
```sh
go build -o baalvpn-server ./server

CGO_ENABLED=0 go build -o baalvpn-client ./client
```

### Server

1. Generate a keypair:
```
./baalvpn-server keygen
```
This creates `server.conf` and `client.conf`.

2. Run:
```
sudo ./baalvpn-server server.conf
```

### Client
1. Copy `client.conf` (generated by keygen) and ensure `SERVER_ADDR` points to the server.

2. Run:
```
sudo ./baalvpn-client client.conf
```
The client will be assigned an IPv6 address from the `fd00:baa1::/32` range.

## Third-party dependencies
* [`github.com/songgao/water`](https://github.com/songgao/water) - wrapper around TUN interfaces for \*nix
* [`golang.zx2c4.com/wintun`](https://git.zx2c4.com/wintun-go) - wrapper around `wintun.dll`
* [`github.com/cloudflare/circl`](https://github.com/cloudflare/circl) - used for ML-DSA, but [only until next Go release](https://go.dev/doc/go1.27#crypto_mldsa)