Port 3073: VCRP — The Chatroom That Wasn't

What This Port Is

Port 3073 sits in the registered ports range (1024–49151). This range is managed by the Internet Assigned Numbers Authority (IANA), which assigns port numbers to applications and protocols that request them. Unlike the well-known ports below 1024 — which require root privileges to bind and host the protocols that run the Internet — registered ports are open to any process on any machine.

IANA lists port 3073 as assigned to VCRP ("Very simple chatroom prot") on both TCP and UDP, with a contact named Andreas Wurf.¹ There is no RFC. There is no specification. There is no evidence of real-world deployment at any measurable scale.

What VCRP Was Supposed to Be

The name suggests a lightweight chatroom protocol — something in the spirit of IRC but simpler. The "very simple" framing implies intentional minimalism, possibly a personal or academic project that wanted its own port number before the work was done.

Whether VCRP was ever implemented, tested, or shipped anywhere is not documented. It's not referenced in any standards body. It doesn't appear in Wireshark's protocol library. It's essentially a name attached to a number, filed with IANA at some point in the past, and then left alone.

If You See Traffic on This Port

If port 3073 is active on a machine you're investigating, it's almost certainly not VCRP. More likely candidates:

• A game client or server (many games use ports in this range for session traffic)
• A proprietary application with no formal registration
• A development or testing service bound to a convenient open port

To check what's actually listening:

# Linux / macOS
sudo lsof -i :3073
sudo ss -tlnp sport = :3073

# Windows
netstat -ano | findstr :3073

The process name and PID in the output will tell you more than the port number ever will.

Why These Ghost Registrations Exist

IANA's registry was designed to prevent collisions — if two applications claim the same port, traffic gets confused. The registration process is intentionally low-friction, which means developers can reserve a port for a protocol that's still in design or development.

Most registered ports reflect real, deployed software. Some reflect protocols that were announced, partially built, and then abandoned. Port 3073 appears to be the latter: a registration that outlived whatever project it was attached to.

The port number itself is harmless. The reservation just means that if VCRP ever does surface, it has a home to go to.