Port 2498: ODN-CasTraq — A Registered Ghost

What Range This Port Belongs To

Port 2498 sits in the registered ports range (1024–49151), also called user ports. This range is managed by IANA — the Internet Assigned Numbers Authority — which maintains a registry of service names and port numbers so that applications don't accidentally collide.

The registered range is different from the well-known ports (0–1023), which are reserved for foundational protocols like HTTP (80), HTTPS (443), and SSH (22). Registered ports are claimed by applications and services through an IANA registration process, but the barrier is lower and the registry is far less curated.

The IANA Assignment

IANA records port 2498 as assigned to a service called ODN-CasTraq on both TCP and UDP.¹ The registrant is listed as Richard Hodges.

That's where the trail ends.

There is no public documentation of what ODN-CasTraq is or was. No RFC. No product page. No company that publicly claims it. The name suggests some combination of "ODN" (possibly an organization or product name) and "CasTraq" (likely case tracking). But what kind of cases, for what system, built by whom — unknown.

This is not unusual for the registered ports range. Thousands of entries were submitted over the decades by developers, companies, and contractors who had legitimate internal uses for a port assignment but never built software that saw wide deployment. Some of those companies no longer exist. Some products were renamed. Some registrations were simply abandoned.

The IANA registry doesn't expire port assignments. A name can sit there indefinitely, technically claimed, practically orphaned.

How to Check What's Listening on This Port

If you see activity on port 2498 on a system you manage, don't assume it's ODN-CasTraq. The real-world use of any port is determined by what software is actually running, not by what IANA has registered.

On Linux or macOS:

# Show what process is listening on port 2498
sudo lsof -i :2498

# Or with ss (Linux)
ss -tlnp | grep 2498

On Windows:

# Show listening ports and associated processes
netstat -ano | findstr :2498

The process ID returned will tell you exactly what software has opened the port. Cross-reference it with your process list to identify the application.

Why Ghost Assignments Matter

The registered ports range contains thousands of entries in various states of relevance. Some are actively used by major software. Some are used by niche enterprise applications that will never appear in a web search. And some, like port 2498, are registered but effectively invisible.

This matters for a few reasons:

Firewall policy. A port being "registered" doesn't mean traffic on it is legitimate. Conversely, traffic on an obscure registered port isn't inherently suspicious — it might be perfectly normal enterprise software that simply isn't well-documented publicly.

Port scanning. When security tools scan a network and find port 2498 open, they often can't identify the service. That ambiguity requires manual investigation rather than automated classification.

The registry as ground truth. IANA's registry reflects what was registered, not what's actually in use. The gap between those two things grows wider the further you get from the well-known ports.

Port 2498 is a small example of a larger truth: the port registry is a historical artifact as much as a technical reference. It records intentions and registrations, but the Internet runs on software, not paperwork.