Port 2853: ISPipes — A Registered Port with a Missing Service

Port 2853 sits in the registered port range (1024–49151), carrying an official IANA assignment to a service called ISPipes, registered by an individual named Rajesh Nandyalam. Both TCP and UDP are listed. Beyond that entry in the registry, ISPipes has left almost no trace on the Internet — no RFC, no documentation, no known implementations. ¹

The Registered Port Range

Ports from 1024 to 49151 are called registered ports. Unlike the well-known ports below 1024, they don't require elevated privileges to bind. Anyone can apply to IANA to register a port for a service, and IANA maintains the list. The catch: registration is voluntary, the list is enormous, and not every registered service survives into actual use.

Port 2853 appears to be one of those registrations that staked a claim and then went quiet. The name exists. The service does not seem to. ²

Security Scanners Have Noticed

Some security databases flag UDP port 2853 as having been used by malware — specifically, trojans that borrowed the port for command-and-control communication at some point. This doesn't mean traffic on port 2853 is malicious. Attackers routinely pick obscure registered ports precisely because they blend into the noise of legitimate-looking port numbers. An unrecognized service on an obscure port is easier to miss than something running on a well-known one. ³

If you see unexpected traffic on 2853, that's reason to look closer, not panic.

How to Check What's Using This Port

Linux/macOS:

# Show which process is listening on port 2853
ss -tlnp | grep 2853
lsof -i :2853

Windows:

netstat -ano | findstr :2853

The PID in the last column can be cross-referenced in Task Manager to identify the process.

Why Unrecognized Ports Still Matter

The port registry exists so that services can coexist without collision. Even a forgotten registration like ISPipes serves a purpose: it reserves that number so nothing else can claim it officially. Whether the service behind the reservation still exists is a separate question.

This is one of the quiet corners of the Internet's address space — formally named, practically empty.