Port 2938: SM-PAS-1 — A Name With No Story

Port 2938 sits in a peculiar position: it has a name in the IANA registry — SM-PAS-1 — but that name leads nowhere. No RFC. No documentation. No known service. No organization publicly claiming it.

It is registered but unexplained.

The Registered Port Range

Port 2938 falls in the registered port range (1024–49151), sometimes called "user ports." This range sits between the well-known ports (0–1023, which require elevated privileges and house the protocols everyone knows: HTTP, SSH, DNS) and the dynamic/ephemeral ports (49152–65535, which operating systems hand out temporarily to client connections).

Registered ports are meant to be claimed by applications and services through IANA. They don't require special OS privileges to bind to, but they carry an implicit promise: something specific is supposed to live here. The registration exists so two different applications don't accidentally step on each other.

That promise is only as strong as the documentation behind the registration.

SM-PAS-1: A Ghost Registration

IANA lists port 2938 (TCP and UDP) under the service name sm-pas-1.¹ The designation suggests a series — presumably sm-pas-2, sm-pas-3, and so on occupy nearby ports — but what SM-PAS stands for, what organization registered it, and whether any software has ever actually used it are questions the public record cannot answer.

This is not unusual. The registered port range was looser about requiring documentation for many years. Port names were claimed, organizations changed, products were discontinued, and the registry was left holding a label with no story behind it.

SM-PAS-1 is a ghost: registered, present, and silent.

No Known Unofficial Uses

Port scanners and security databases do not flag port 2938 as commonly observed in the wild for any particular service, malicious or legitimate.² If something is using this port, it is not doing so loudly enough to show up in aggregate network data.

How to Check What Is Using This Port

If port 2938 appears in your environment, here is how to find out what is actually listening:

On Linux or macOS:

ss -tlnp | grep 2938
# or
lsof -i :2938

On Windows:

netstat -ano | findstr :2938

Then take the process ID from the output and look it up:

# Linux/macOS
ps aux | grep <PID>

# Windows
tasklist | findstr <PID>

Whatever you find is the actual tenant of this port on your system — not the SM-PAS-1 registration, which is more historical artifact than active service.

Why Unassigned and Ghost Ports Matter

The port registry is a coordination mechanism, not a guarantee. When a port carries a clear, documented service, network administrators can make informed decisions about firewalls, monitoring, and access control. When a port carries a name without documentation — or no name at all — that clarity disappears.

For security, unexpected traffic on an undocumented port deserves scrutiny. There is no baseline to compare against, no RFC to reference, no known behavior to expect. That uncertainty is itself worth noting.