Port 3633: WACP — A Registered Port with No Remaining Owner

What Port 3633 Is

Port 3633 sits in the registered ports range — numbers 1024 through 49151 that IANA tracks in its Service Name and Transport Protocol Port Number Registry. These aren't randomly assigned; companies and developers submit requests to associate their software with a specific number, and IANA records it.

For port 3633, that request was filed in November 2002. The registrant was Wyrnix, and the service was called WACP — the Wyrnix AIS port — registered for both TCP and UDP.¹

The "AIS" almost certainly refers to the Automatic Identification System, the maritime tracking protocol that ships use to broadcast their position, speed, and identity to nearby vessels and shore stations. Wyrnix apparently built software in that space.

The Problem: Wyrnix Is Gone

There's no trace of Wyrnix online. No website, no archived documentation, no forum posts from users, no GitHub repositories, no LinkedIn entries. Whatever WACP was — a server, a client, a data aggregation tool for maritime AIS feeds — the software and the company that made it have both disappeared.

The IANA registration remains. Port 3633 is still "taken" in the registry. But there's no protocol specification, no implementation, no one maintaining it. It's a reserved parking space for a car that no longer exists.

Why This Matters

The registered ports range has thousands of these. Numbers claimed during the dot-com era or early 2000s by companies that folded, pivoted, or simply stopped caring. The IANA registry is a historical record as much as a technical one — a ledger of software projects, some thriving, some forgotten.

Port 3633 won't cause you problems. Nothing should be listening on it by default. But if you see traffic on it, that's worth investigating, because no legitimate modern software claims this port as its own.

If You See Traffic on Port 3633

Unexpected traffic on an obscure registered port usually means one of three things: a misconfigured application that picked an arbitrary port, custom internal software assigned this number for convenience, or something you want to look at more carefully.

Check what's listening with these commands:

Linux/macOS:

# Show what process is using port 3633
sudo lsof -i :3633

# Or with ss
ss -tlnp | grep 3633

# Or with netstat
netstat -tlnp | grep 3633

Windows:

netstat -aon | findstr :3633

The process ID from these commands will tell you exactly what software opened the port.

Neighboring Ports

For context on what lives nearby in the registry:

• Port 3632 — distcc, the distributed C/C++ compiler — a real, widely used tool²
• Port 3634 — Also unassigned
• Port 3659 — Apple SASL, used by Apple services³