Port 2438: MSP — Registered, Undocumented

Port 2438 sits in the registered ports range and carries an IANA service name — MSP — assigned on both TCP and UDP. But IANA's registry lists no description, no RFC, no contact, and no explanation of what "MSP" stands for in this context.¹

It's not unassigned. It's something stranger: a registered port that was claimed and then apparently abandoned without documentation.

The Registered Ports Range

Port 2438 falls in the registered ports range (1024–49151), sometimes called user ports. These ports are assigned by IANA on a first-come, first-served basis — any developer or organization can request one for a specific service or protocol, as long as the port isn't already taken.

Unlike well-known ports (0–1023), registered ports don't require the same depth of documentation or an associated RFC. Some were registered decades ago and the original services never shipped, were abandoned, or simply weren't documented when submitted.

Port 2438 appears to be one of these orphaned registrations.

What "MSP" Could Mean

"MSP" is an acronym with many possible expansions: Message Service Protocol, Management Service Protocol, Messaging Service Protocol — none of which are obviously associated with port 2438 in any public documentation.

There is an older Message Send Protocol (also abbreviated MSP) assigned to port 18, defined in RFC 1159. Port 2438's "MSP" appears unrelated to that protocol, but the connection, if any existed, has been lost.²

No real-world software is publicly documented as using port 2438/MSP for its primary operation.

What Gets Observed on This Port

The SANS Internet Storm Center logs occasional scanning activity targeting port 2438, consistent with broad automated reconnaissance that sweeps across the registered ports range.³ This is noise, not signal — scanners probe thousands of ports on the same pass.

There's nothing notable: no known exploits, no known malware families, no documented vulnerability tied to this port.

How to Check What's Using Port 2438

If you see activity on port 2438 on your own system or network, it's almost certainly an application that chose this port arbitrarily — not because of the IANA assignment:

Linux/macOS:

# Show what's listening on port 2438
ss -tlnp sport = :2438
# or
lsof -i :2438

Windows:

netstat -ano | findstr :2438

Then match the PID from netstat against Task Manager or tasklist to identify the process.

Why Orphaned Registrations Matter

The registered ports range contains thousands of entries like this — claimed, never documented, never updated. They're harmless in themselves, but they're part of why port databases sometimes return misleading results.

When a security tool flags "MSP on port 2438" as a risk, it's doing so because the port has a name, not because the name means anything. The label is vestigial. What matters is what's actually running, not what IANA called it in a registration that may predate the World Wide Web.