Port 3165: Newgenpay Engine Service — A Name in the Registry, Quiet in Practice

What Port 3165 Is

Port 3165 sits in the registered port range (1024–49151). IANA lists it as assigned to the Newgenpay Engine Service on both TCP and UDP — a payment processing engine tied to NewGenPay, a company that handled e-commerce payment transactions in the early 2000s.¹

Beyond that registration, documentation is essentially nonexistent. No RFC was ever written for it. The service isn't part of any widely deployed infrastructure you'd encounter today.

The Registered Port Range

Ports 1024 through 49151 are registered ports. Unlike the well-known ports below 1024 — where SSH lives at 22, HTTP at 80, HTTPS at 443 — registered ports don't require elevated OS privileges to bind. Any application can use them.

The registration process exists so vendors can stake out a port number for their service, reducing the chance of conflicts. In practice, registration doesn't guarantee a port is actually used, and it doesn't prevent other software from using the same port on a given machine. It's a coordination mechanism, not enforcement.²

Port 3165 is a good example of how this plays out: a company registers a port, builds a product, and years later the registration outlives the product's relevance. The number stays in the registry; the traffic disappears.

What You Might Actually See on Port 3165

Almost certainly nothing tied to Newgenpay. If you see activity on port 3165, it's more likely:

• A custom application using it as an arbitrary high-numbered port
• Ephemeral traffic — operating systems use the registered range for outbound connections, and port 3165 can appear as a source port in normal browsing and application traffic
• Scanning activity — automated scanners probe all ports routinely

How to Check What's Listening

# Linux / macOS
ss -tlnp | grep 3165
lsof -i :3165

# Windows
netstat -ano | findstr :3165

If something is listening, the process ID will tell you what it is. On Linux, lsof -p <pid> shows the full picture.

Why Unassigned-in-Practice Ports Matter

The port space isn't a neat map where every number has a clear tenant. The registered range is largely a patchwork of active services, abandoned registrations, and squatters. When a security scanner flags unexpected activity on a port like 3165, the right question isn't "what's the registered service?" — it's "what's actually running, and should it be?"

The registry tells you what a port was supposed to be. Your own system tells you what it is.