Port 2783: AISES — A Registered Ghost

What Range This Port Belongs To

Port 2783 falls in the registered ports range (1024–49151). These ports are not reserved for system services the way the well-known ports (0–1023) are, but they are intended to be claimed by specific applications through IANA registration. The idea is orderly: you build a protocol, you register a port, other software knows where to find you.

It works better in theory than in practice.

The IANA Registration

Port 2783 is registered with IANA under the service name aises, for both TCP and UDP.¹ The IANA entry lists a contact: Daniel Grazioli at pgaero.co.uk.

That domain — pgaero.co.uk — points to Penny & Giles Aerospace, a British company that manufactured flight data recorders, air data systems, and cockpit instrumentation. Curtiss-Wright acquired Penny & Giles in 2002.² The domain now resolves to nothing.

AISES almost certainly stands for something related to aircraft information or embedded systems — possibly an internal ground-support or data-acquisition protocol used with Penny & Giles hardware. But there is no RFC, no public specification, no archived documentation. The registration is real. The protocol, as far as the public record is concerned, is a ghost.

What This Means in Practice

If you see traffic on port 2783, it is almost certainly not AISES. It is more likely:

• A custom application that picked this port arbitrarily
• Developer tooling or a local service using a non-conflicting port
• Scanning traffic probing open ports

The AISES registration poses no practical conflict for most deployments — the protocol, if it ever ran at scale, ran inside aerospace ground-support environments, not on the open Internet.

How to Check What Is Listening

If you see activity on port 2783 and want to know what is using it:

macOS / Linux:

sudo lsof -i :2783

or

sudo ss -tlnp | grep 2783

Windows:

netstat -aon | findstr :2783

Then match the PID to a process in Task Manager.

Why Ghost Registrations Exist

The registered port range is large — over 48,000 ports — and IANA does not aggressively police it. Companies register ports for internal protocols, products get discontinued or acquired, contacts become unreachable, and the registration persists indefinitely. Port 2783 is one of dozens of entries in the IANA registry with descriptions that simply repeat the service name and nothing else.

This is not a flaw, exactly. The alternative — a registry that expires registrations and reclaims ports — would create its own instability. So the ghost registrations accumulate, quiet monuments to projects that shipped, were acquired, or simply ended.