Port 2936: OTPatch — A Reserved Port with No Public Story

What Range This Port Belongs To

Port 2936 sits in the registered ports range (1024–49151). These ports are managed by IANA and can be claimed by organizations or individuals for specific services. Unlike the well-known ports (0–1023), registered ports don't require root privileges to bind on most systems — any user process can open one.

The Registration

IANA lists port 2936 as assigned to a service called OTPatch, registered by Brett Goldstein at OpenTable (the restaurant reservation company). Both TCP and UDP are listed.

That's where the trail ends. There is no public RFC, no open protocol specification, no developer documentation, and no known open-source software that implements or references "OTPatch." The "OT" almost certainly stands for "OpenTable," suggesting this was an internal service — a patching tool or update mechanism used within OpenTable's infrastructure — that was registered with IANA but never publicly described.

This happens more than you'd think. Companies register ports with IANA to avoid conflicts with their own infrastructure, then use those ports for proprietary internal services that the outside world never sees. The port is technically assigned but practically invisible.

Is Anything Actually Listening on Port 2936?

On most systems: nothing. If you want to check your own machine:

# macOS / Linux
sudo lsof -i :2936

# Linux (alternative)
ss -tlnp | grep 2936

# Windows
netstat -ano | findstr :2936

If something shows up, it's not OTPatch — it's something else that happened to pick this port. That could be legitimate software, a misconfigured service, or something worth investigating.

Why Unassigned (and Ghost-Assigned) Ports Matter

The registered port range exists so that services can have stable, predictable home addresses. A port number in the IANA registry signals "something lives here — route accordingly, don't conflict."

But registrations like port 2936 reveal the limits of that system. The registry is not audited for accuracy. Companies register ports, services get discontinued, contact information goes stale, and the registration sits there indefinitely — blocking the port from being reassigned to something new, while providing no actual guidance to anyone who encounters traffic on it.

Port 2936 isn't broken. It just fell through the cracks between "assigned" and "useful."