What This Port Is
Port 2545 sits in the registered ports range (1024–49151), the middle tier of the port numbering system. These ports are administered by IANA, the Internet Assigned Numbers Authority, which maintains the official registry of which service owns which number.
IANA lists port 2545 as assigned to a service named sis-emt, registered by an individual named Bill Crawford, on both TCP and UDP. That's where the paper trail ends. There is no RFC, no technical specification, no vendor documentation, and no known deployment of anything called "sis-emt" anywhere on the public Internet.1
The Ghost Registration Problem
The IANA registered ports range contains thousands of ports like this — names that someone submitted, a registration that IANA accepted, and then nothing. No product shipped. No protocol was specified. No one ever listened on that port at scale.
This happens for several reasons. Companies register ports speculatively for products that never launched. Developers register ports for internal tools that never needed a public standard. Some registrations are simply abandoned when projects ended. The result is a registry full of names that occupy port numbers without contributing any protocol to the Internet.
Port 2545 is one of these. "sis-emt" could stand for almost anything. Without documentation, the name is a placeholder — the bureaucratic memory of an intention that didn't become a protocol.
Scanning Activity
Despite having no known legitimate use, port 2545 does attract attention. SANS Internet Storm Center logs regular scanning activity against this port from IP addresses conducting broad reconnaissance sweeps.2 This is not specific to port 2545 — automated scanners probe the entire port range continuously, looking for anything listening. An unassigned port receiving scans means nothing by itself.
What to Do If You See It
If port 2545 appears in your network traffic or firewall logs, the question isn't "what protocol is this?" — it's "what software opened this port?"
To find out what's listening:
On Linux or macOS:
On Windows:
The process ID returned will tell you exactly which application claimed the port. From there, check whether that application is expected, legitimate, and should be accepting connections.
Why Unassigned Ports Matter
The three-tier port system — well-known (0–1023), registered (1024–49151), dynamic (49152–65535) — exists so that software can find each other without guessing. Port 80 is HTTP because everyone agreed it would be. The system works because most ports are documented.
Ghost registrations like port 2545 don't break the system, but they do represent its limits. IANA can register a name, but it cannot force a protocol into existence. The registry reflects intent, not reality. Port 2545 was intended for something. What that something was, only Bill Crawford knows.
¿Fue útil esta página?