What This Port Is
Port 2675 sits in the registered ports range (1024–49151). IANA has assigned it to a service listed as TTC ETAP, over both TCP and UDP. The registrant on file is Daniel Becker.
That's roughly where the paper trail ends.
The Registered Ports Range
Registered ports occupy the middle tier of the port numbering system:
| Range | Name | Who assigns them |
|---|---|---|
| 0–1023 | Well-known ports | IANA, historically privileged |
| 1024–49151 | Registered ports | IANA, on request |
| 49152–65535 | Dynamic/ephemeral ports | Assigned by the OS at runtime |
Registered ports don't require the same scrutiny as well-known ports. An organization can request a number, provide a service name and contact, and receive an assignment. The service doesn't have to be widely deployed, open-source, or even publicly described. IANA records the name and moves on.
TTC ETAP: What Little Is Known
ETAP is a well-known acronym in power systems engineering — it stands for Electrical Transient Analyzer Program, a major software platform used to model and simulate electrical power systems.1 The company behind it, Operation Technology, Inc., was founded in 1986 and later acquired by Schneider Electric.2
TTC likely refers to the software's licensing or communication infrastructure — possibly "TTC" as an internal product or module code — but no public RFC, technical specification, or official documentation connects "TTC ETAP" to port 2675. Even ETAP's own installation guides point to different ports for their license manager (port 6260).3
The most likely scenario: port 2675 was registered for an internal or legacy ETAP communication protocol that never saw broad adoption, was superseded, or was simply never publicly documented.
What's Actually Listening Here
On any random machine, almost certainly nothing. You can verify with:
Linux/macOS:
Windows:
If something is listening, cross-reference the process ID with your system's process list. Unknown listeners on registered ports are worth investigating.
Why Obscure Assignments Like This Matter
The IANA registry is both a coordination mechanism and a historical record. When a port is assigned — even to something nobody uses — it's taken out of the pool of "anyone can grab this without conflict." That's the point. The registry prevents two independent developers from shipping software that both claim port 2675, causing silent collisions in the field.
The tradeoff is that the registry also accumulates assignments that outlast their software, their companies, and sometimes their documentation. Port 2675 may never be revoked. It may sit in the registry long after anyone remembers what TTC ETAP was.
There are roughly 6,000 registered port assignments. Many of them carry the same quiet mystery this one does: a name, a contact, and silence.
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