Port 3707: rt-event-s — The Ghost Registration

What Port 3707 Is

Port 3707 sits in the registered ports range (1024–49151). These ports aren't reserved for the operating system — they're allocated by IANA to specific services on request, so different applications don't accidentally collide.

IANA registered port 3707 in February 2003 under the name rt-event-s — "Real-Time Event Secure Port." ¹ That's the entirety of what's known about it. No RFC was written. No implementation shipped. No software claimed the name. The service exists in the registry the way a name exists on a deed to an empty lot.

Who Actually Uses It

Uniview, a manufacturer of IP security cameras and NVRs, uses port 3707 as part of its P2P (peer-to-peer) cloud connectivity stack, alongside ports 3702 and 3705. ² When a Uniview camera registers itself with the company's cloud infrastructure for remote viewing, port 3707 is one of the doors it knocks on.

This is squatting, technically — using a registered port that belongs to someone else's abandoned claim. It's common. The registered ports range has thousands of names attached to services that never shipped, and the practical Internet fills the vacuum.

Scanning Activity

SANS Internet Storm Center logs regular scanning activity against port 3707. ³ This is routine for any registered port — automated scanners probe everything. There's nothing specific to this port that makes it a target; it's just visible.

How to Check What's Listening

If you see traffic on port 3707 and want to know what's using it:

macOS / Linux:

sudo lsof -i :3707

Windows:

netstat -ano | findstr :3707

The process ID in the output can be matched against Task Manager (Windows) or ps (Unix) to identify the application.

If you're on a network with Uniview cameras, finding port 3707 in use is expected and benign. If you're not — it's worth investigating.

Why Unassigned Ports Matter

The registered ports range exists to prevent chaos. Without it, two applications that both want port 3707 would have no way to arbitrate. IANA's registry is the authority — but registration doesn't guarantee implementation, and implementation doesn't require registration. The real-world Internet and the official registry diverge constantly.

Port 3707 is a small example of both facts. A name with no service. A service with someone else's name.