Port 2523: Qke LLC V.3 — Registered, Forgotten

What Range This Port Belongs To

Port 2523 sits in the registered ports range (1024–49151). These ports are assigned by IANA to specific applications and services — not on a first-come-first-served basis like ephemeral ports, but through a formal registration process. Registered ports are meant to be claimed and documented.

The Official Assignment

The IANA registry lists port 2523 as qke-llc-v3 — "Qke LLC V.3." The registration contact is Joerg Niehoff, with an email address at alcatel-ke.de, suggesting a connection to Alcatel (now Nokia).¹

That's where the paper trail ends.

There's no RFC. No protocol specification. No product documentation. No forum threads from engineers troubleshooting it. The name "V.3" implies earlier versions existed, which makes the silence more conspicuous. Whatever Qke LLC was — an internal Alcatel protocol, a product, a service — it didn't leave a public footprint.

What This Means in Practice

For most purposes, port 2523 behaves like an unassigned port. The registration is real, but the service it names is either:

• Proprietary and internal — used inside Alcatel's products without public documentation
• Defunct — the protocol was retired and the registration was never cleared
• Both — it was internal, and then abandoned

If you encounter port 2523 open on a system you manage, don't assume it's Qke LLC V.3. No widely deployed software uses this port by default. Something else is almost certainly listening.

How to Check What's Listening

Linux/macOS:

sudo ss -tlnp | grep 2523
# or
sudo lsof -i :2523

Windows:

netstat -aon | findstr :2523
tasklist | findstr <PID>

These commands will show you which process has the port open — and that answer is almost certainly more useful than any historical record.

Why Unassigned (and Ghost-Assigned) Ports Matter

The port number space is a shared resource. When IANA assigns a number to a service, it's supposed to be a permanent, documented reservation. Port 2523 reveals a real problem: registrations don't expire, services do. The port is technically "taken," but nothing meaningful is using it.

This matters because:

• Network scanners will flag port 2523 as registered and show the "Qke LLC V.3" label, which is technically accurate and practically useless
• Firewall rule writers can't find documentation about whether to block or allow it
• Security auditors have to treat it like an unknown until they check what's actually running

A ghost registration is arguably worse than an unassigned port — at least an unassigned port doesn't pretend to have an answer.