STEP 01
INSTALL
Run LanParty-Setup.exe. It installs the app plus the TAP-Windows virtual network driver if you don't already have it — Windows may ask you to trust “OpenVPN Inc”, say yes.
TOOL · WINDOWS · OPEN SOURCE
LanParty
A virtual LAN for old-school multiplayer, over the internet. One friend hosts, everyone else joins, and every machine appears on a shared network — LAN lobby discovery, broadcasts, even IPX-era protocols all work, because the tunnel carries raw Ethernet frames.
WHAT IT IS
Think tiny self-hosted Hamachi: one small app, no accounts, no third-party servers. Every player's copy of LanParty opens a TAP-Windows virtual network adapter — a raw Ethernet device — and the host acts as a virtual switch, forwarding frames to whoever they're addressed to and flooding broadcasts to everyone. That flooding is what makes an old game's "LAN lobby" discovery work over the open internet as if everyone were plugged into the same switch.
Built because the old multiplayer — the kind bound to a physical LAN cable — deserved to keep working. No re-releases, no matchmaking service, no publisher permission required.
GETTING A PARTY RUNNING
STEP 02
LAUNCH
Open LanParty from the Start Menu. It asks for admin — it needs that to manage the virtual network adapter.
STEP 03
HOST OR JOIN
Hosting: click Start hosting, forward UDP 7777 on your router, then Copy join address and send it. Joining: paste the address you were sent and click Join.
STEP 04
PLAY
When the log says “connected! you are 10.67.0.x”, open your game and host or join a LAN lobby like it's 1999.
SECURITY
v0.3PARTY CODE → KEY
The code is stretched with Argon2id (64 MB, ~0.5 s) into a 32-byte key. Guessing a code means paying that cost per guess; the host also rate-limits attempts, so online guessing is hopeless.
FRESH KEYS EVERY SESSION
Joining is one round trip, authenticated with the key and mixed with fresh X25519 keys — a recording of one session can't be replayed into another.
EVERY PACKET ENCRYPTED
XChaCha20-Poly1305, authenticated, with a per-direction counter and a 64-packet replay window — the same scheme WireGuard uses.
SILENT TO STRANGERS
The host never replies to anything that doesn't authenticate. To a port scanner, the party looks like a closed port.
What it does not do: hide that you're running LanParty from someone watching your traffic, or protect you from a friend's PC that's already compromised — you're on a real LAN with them, same as a physical LAN party.
COMMAND LINE
The exe also works from an admin terminal:
lanparty host [-port 7777] [-code XXXX-XXXX]
lanparty join <host-ip:port#CODE> [-name You] -no-ipconfig skips the automatic 10.67.0.x address if you'd
rather set it yourself.
GOOD TO KNOW
- Windows only (TAP-Windows). DOS-era IPX games running inside DOSBox should use DOSBox's own IPXNET instead.
- All traffic relays through the host — everyone's ping is their ping to the host.
- The host needs a forwarded port. CGNAT ISPs can't host — someone else hosts.
- The installer isn't code-signed, so SmartScreen shows “unknown publisher” — More info → Run anyway.
BUILT WITH
Go, a TAP-Windows virtual adapter, and Inno Setup for the installer. MIT licensed — the source, the build script, and the installer script are all on GitHub.
