Port 2946: FJSVmpor — A Fujitsu Ghost

What This Port Is

Port 2946 sits in the registered port range (1024–49151). These ports are assigned by IANA to specific applications and services — not claimed on a first-come basis like ephemeral ports, and not treated as universal infrastructure like well-known ports below 1024.

IANA lists port 2946 as assigned to FJSVmpor, a Fujitsu service, on both TCP and UDP. That's the extent of the public record. No RFC. No Fujitsu documentation describing what FJSVmpor does, what product uses it, or why it needs a registered port.¹

This is more common than it sounds. Companies register ports during product development or internal use, and those registrations outlive the documentation — or the products themselves.

What's Actually on This Port

In practice: probably nothing, on most machines.

FJSVmpor appears to be associated with Fujitsu enterprise software — likely server management tooling from their PRIMERGY or middleware lines — but no public documentation connects the dots. If you're running Fujitsu infrastructure software and see activity on port 2946, that's likely the source. Otherwise, it should be closed.

No significant malware campaigns have been documented using port 2946. No CVEs reference it. It's not on the usual lists of ports associated with trojans or backdoors.

How to Check What's Listening

If you see port 2946 open on a system and want to know why:

On Linux/macOS:

sudo ss -tlnp | grep 2946
# or
sudo lsof -i :2946

On Windows:

netstat -ano | findstr :2946
# Then look up the PID:
tasklist | findstr <PID>

If something is listening and you don't recognize it, that's worth investigating — not because this port is flagged, but because any unexpected listener deserves a name.

Why Unassigned-in-Practice Ports Matter

The registered port range contains thousands of entries like this one — technically assigned, practically undocumented. They matter for a few reasons:

Firewall policy. Most organizations block all ports by default and open only what's needed. A port like 2946 should be closed unless you're running the specific Fujitsu software that uses it.

Anomaly detection. Unexpected traffic on an obscure registered port is a signal worth examining. Not because the port is dangerous, but because the unexpectedness is the data point.

Port exhaustion isn't real, but namespace is. The registered range has roughly 48,000 slots. IANA tracks assignments to prevent collisions. Even ghost registrations like this serve that purpose.