Port 1749: Aspen Services — Registered, Forgotten

What Port 1749 Is

Port 1749 sits in the registered port range (1024–49151). IANA lists it as assigned to a service called aspen-services, registered for both TCP and UDP. The registrant is named in IANA's records. The service itself has left almost no public documentation.

This happens. Organizations or individuals register ports with IANA, the registration is accepted, and then the project stalls, pivots, or quietly disappears. The port number stays claimed. The Internet moves on.

The Registered Range

Ports 1024–49151 are registered ports. Anyone can apply to IANA to reserve a port number for a specific service. IANA reviews applications and, when approved, adds the service name and contact to the registry.¹

This is different from the well-known ports (0–1023), which are tightly controlled and assigned to foundational protocols: HTTP, HTTPS, SSH, DNS. Registered ports are for applications that want an official, consistent number — so their users don't have to configure one manually.

But registration doesn't guarantee a service survives. Port 1749 is evidence of that.

A Malware Footnote

In the early 2000s, variants of W32.Gaobot — a worm that spread through network shares and unpatched Windows vulnerabilities — used port 1749 as a communication channel.² Gaobot connected infected machines to IRC servers for remote control, and some variants used this port as part of that infrastructure.

Gaobot is long dead as an active threat. Its mention here is historical, not a warning.

What You'll Actually Find on Port 1749

Probably nothing. If you see port 1749 open on a machine, it's almost certainly an application that picked a high-numbered port for its own use — a developer's local service, a game server, an internal tool. The "aspen-services" registration doesn't tell you what that application is.

To find out what's actually using it:

macOS / Linux:

lsof -i :1749

Windows:

netstat -aon | findstr :1749

Then take the process ID (PID) and look it up in Task Manager or with:

ps -p <PID>   # macOS/Linux

Why Unassigned-in-Practice Ports Matter

The registered port range has over 48,000 slots. Many are actively used. Some are registered and forgotten. Some were never registered but became standard through widespread adoption anyway.

The gap between "registered" and "used" is where real network forensics happens. When an unexpected port is open on a server, you don't look it up and trust the registry entry. You look at the process. You verify the binary. You ask why it's listening.

The IANA registry tells you what a port was intended for. The actual machine tells you what it's doing.