Port 3063: ncadg-ip-udp — A Registered Port Nobody Knocks On

What This Port Is

Port 3063 sits in the registered ports range (1024–49151). IANA has assigned it a name: ncadg-ip-udp, which stands for Network Computing Architecture Datagram over IP using UDP.

That name is a mouthful for a relatively simple idea. NCAdg is the connectionless (datagram) variant of DCE/RPC — the Distributed Computing Environment's Remote Procedure Call protocol. Where most RPC uses a reliable TCP connection (ncacn), the datagram variant fires calls over UDP and accepts the tradeoffs: no guaranteed delivery, no ordered sequencing, no connection overhead.

It was designed for scenarios where speed mattered more than reliability — fast local queries, status checks, lightweight distributed operations where a dropped call could simply be retried.

Why You Won't See It

The honest answer: this port's moment passed before most networks were built.

Modern Windows RPC over UDP doesn't use a fixed port like 3063. Instead, clients contact the endpoint mapper at port 135, which hands back whatever dynamic port the service registered. The port 3063 assignment is a legacy artifact from an era when protocols were assigned static ports before dynamic port negotiation became standard practice. ¹

If you see traffic on port 3063 today, it's worth investigating — not because the port is inherently dangerous, but because legitimate registered services aren't typically using it.

What "Registered" Actually Means

There are three port ranges:

Being a registered port means IANA recorded the assignment. It does not mean the protocol is actively used, widely deployed, or even currently maintained. The registry contains thousands of assignments for protocols that have since been superseded, abandoned, or simply never adopted.

Port 3063 is in that company.

How to Check What's Listening

If you want to know whether anything is using port 3063 on your system:

macOS / Linux:

sudo lsof -i :3063
sudo ss -tulpn | grep 3063

Windows:

netstat -ano | findstr :3063

An empty result is the expected and healthy outcome.