Port 3023: Registered, Forgotten

What Port 3023 Is

Port 3023 sits in the registered ports range (1024–49151). These are ports that applications and services can request from IANA — the Internet Assigned Numbers Authority — to stake a claim on a number. The claim doesn't expire, and IANA doesn't reclaim abandoned registrations.

IANA lists port 3023 as assigned to a service called magicnotes, on both TCP and UDP.¹ What magicnotes was — a notes application, a collaboration tool, something else entirely — is unclear. The software is gone. The registration remains.

The Gap Between Registration and Reality

This is a common condition in the registered port range. A developer files for a port, ships a product, the product dies or pivots, and the port number sits there in the registry forever — officially occupied, practically empty.

Port 3023 is one of thousands in this state. The registry is not a map of what's running. It's a map of what once wanted to run.

Security History

Port 3023 appears in threat databases associated with W32.Trojan.Ranky.FV, an HTTP proxy trojan that turned infected machines into proxy nodes for attackers.² The trojan spread via variants of the Mocbot worm, which exploited a Windows Server Service buffer overflow vulnerability (MS06-040) — a 2006 flaw.

This is typical for unmonitored registered ports: malware picks numbers that sound legitimate, because a port named "magicnotes" raises fewer alarms than something obviously random. The association is historical, not current, but it's a reminder that obscure ports aren't neutral.

What Might Actually Be on Port 3023

In practice, if you see traffic on port 3023, it's almost certainly one of:

• Nothing — most machines leave this port untouched
• A custom application — developers sometimes use ports in the thousands for internal services, tunnels, or development servers
• Something you should investigate — unexpected listeners on registered-but-obscure ports warrant a look

How to Check What's Listening

macOS / Linux:

lsof -i :3023

Linux (alternative):

ss -tlnp | grep 3023

Windows:

netstat -ano | findstr :3023

These commands show you the process name and PID of whatever has claimed the port. If you don't recognize it, that's worth knowing.

Why Unassigned (and Forgotten) Ports Matter

The registered port range was designed to bring order to the chaos of applications claiming numbers at random. In practice, it's a graveyard of defunct software registrations, punctuated by ports that are actively used and well-known.

Knowing this range exists — and that registration doesn't equal activity — is part of understanding what you're actually looking at when you run a port scan. The registry tells you what someone once intended. Only lsof tells you what's actually there.