softlan-vpn/TESTING.md

# MVP Test Guide

This guide is for the manual end-to-end MVP proof:

```text
Windows TAP client -> public QUIC relay -> Linux AF_PACKET gateway -> LAN
```

The MVP is intentionally manual. It does not include an installer, GUI,
production certificates, auth, or end-to-end payload encryption.

## Machines

- Relay: public Linux host reachable over UDP.
- Gateway: Linux machine plugged into the LAN party switch with wired Ethernet.
- Client: Windows 11 machine with TAP-Windows6 installed.

Use the same room code everywhere, for example `ROOM1`.

## Build

On the relay or Linux build host:

```bash
cargo build --release -p lanparty-relay -p lanparty-gateway
```

On Windows, in an Administrator terminal:

```powershell
cargo build --release -p lanparty-client-win
```

The Windows client must run elevated because it opens TAP and edits routes.
The gateway usually needs root because it opens an AF_PACKET raw socket.

## Start The Relay

Use a high UDP port first unless you already want to deal with privileged
`443/udp` binding:

```bash
./target/release/lanparty-relay \
  --listen 0.0.0.0:8443 \
  --dev-cert-der-out relay-cert.der
```

Open inbound UDP for the selected port on the relay host firewall.

Expected relay output:

```text
lanparty-relay configured for 0.0.0.0:8443/udp ...
lanparty-relay listening on 0.0.0.0:8443
```

Copy `relay-cert.der` to the gateway and Windows client. The development
certificate is for `lanparty-relay.local`, so keep
`--server-name lanparty-relay.local` even when `--relay` is an IP address or
another DNS name.

## Start The Gateway

On the LAN gateway machine:

```bash
sudo ./target/release/lanparty-gateway \
  --relay relay.example.net:8443 \
  --server-name lanparty-relay.local \
  --relay-ca-cert ./relay-cert.der \
  --room ROOM1 \
  --iface eth0
```

Use the real wired LAN interface name for `--iface`. Do not use Wi-Fi.

Expected gateway output:

```text
lanparty-gateway connected as peer ...
lanparty-gateway opened AF_PACKET socket on eth0 ...
lanparty-gateway bridging frames; press Ctrl-C to stop
```

Expected relay output:

```text
accepted Gateway peer ... in room ROOM1 ...
```

## Start The Windows Client

In an Administrator terminal on Windows:

```powershell
.\target\release\lanparty-client-win.exe `
  --relay relay.example.net:8443 `
  --server-name lanparty-relay.local `
  --relay-ca-cert .\relay-cert.der `
  --room ROOM1
```

If the Windows machine has multiple TAP-Windows6 adapters, select the intended
one explicitly:

```powershell
.\target\release\lanparty-client-win.exe --list-tap-adapters

.\target\release\lanparty-client-win.exe `
  --relay relay.example.net:8443 `
  --server-name lanparty-relay.local `
  --relay-ca-cert .\relay-cert.der `
  --room ROOM1 `
  --tap-instance-id "{InterfaceGuid-from-the-command-above}"
```

Expected client output:

```text
lanparty-client-win connected as peer ...
relay route pinned before TAP ...
relay route verified after TAP activation ...
TAP driver reports MAC ... and MTU ...
client diagnostics: relay reachable yes gateway connected yes route pinned yes ...
```

The first diagnostics line may show `IP unknown`. After DHCP succeeds, a later
line should show:

```text
DHCP received: 10.x.x.x
```

## What To Verify

1. Relay sees both peers:

```text
accepted Gateway peer ...
accepted Client peer ...
```

2. Client sees the gateway:

```text
gateway connected yes
Connected to LAN gateway
```

3. Windows TAP gets an address from the LAN:

```powershell
Get-NetIPAddress | ? InterfaceAlias -like "*TAP*"
```

4. ARP and ping work from the TAP-side address:

```powershell
arp -d *
ping -S <tap-ip> <lan-host-ip>
arp -a
```

5. The LAN switch learns the remote client MAC on the gateway port.

Use the switch UI or CLI and look for the client MAC printed by the Windows
client. It should appear on the physical port connected to the Linux gateway.

6. A real LAN game discovers or joins a LAN server.

This is the practical MVP acceptance test.

## Useful Log Signals

Relay frame forwarding:

```text
relay frame room=ROOM1 ... action=Forwarded drop_reason=- targets=1
```

Gateway LAN traffic:

```text
gateway frame interface=eth0 direction=LanToRemote ... action=Forwarded
gateway frame interface=eth0 direction=RemoteToLan ... action=Forwarded
```

Client health:

```text
Relay RTT: 23 ms
Broadcast traffic flowing
```

Drops that can be normal during testing:

```text
drop_reason=UnknownDestination
drop_reason=DatagramBudget
drop_reason=RateLimit
```

Drops that should be investigated if they dominate:

```text
drop_reason=Malformed
drop_reason=UnauthorizedSourceMac
drop_reason=ControlPlaneEtherType
```

## Troubleshooting

If the client says `Waiting for LAN gateway`, check that the gateway uses the
same room code and is connected to the same relay.

If the client says `Waiting for TAP IP`, DHCP is not making the full round trip.
Check relay/gateway frame logs for broadcast traffic and check that the gateway
is on wired Ethernet.

If startup fails with a TAP MAC mismatch, disable/enable the TAP adapter or
reinstall TAP-Windows6 so Windows reloads the `NetworkAddress` value. Do not
continue with a mismatched MAC.

If startup says the relay route changed, stop. The client is refusing to run
because Windows would route the relay connection through the tunnel.

If ping fails but DHCP worked, check Windows firewall, the target LAN host
firewall, and whether the LAN subnet conflicts with the client's home LAN.
Uncommon LAN subnets such as `10.73.42.0/24` are safer than `192.168.0.0/24`.

## Cleanup

Stop client, gateway, and relay with Ctrl-C. The Windows client restores the TAP
route policy when it exits normally.

Keep `lanparty-client-identity.json` if you want the same virtual MAC on the
next run. Delete it only when you intentionally want a new client identity.

## Report Back

For a useful test report, capture:

- relay command and relay logs
- gateway command and gateway logs
- client command and client logs
- Windows TAP MAC and IP
- ping result from `<tap-ip>` to a LAN host
- switch MAC-table entry for the Windows client MAC
- LAN game discovery or join result