Port 3591: LOCANIS G-TRACK — The Registered Ghost

What Port 3591 Is

Port 3591 sits in the registered ports range (1024–49151). These ports are assigned by IANA — the Internet Assigned Numbers Authority — to specific services upon application. Unlike the well-known ports below 1024, registered ports don't require elevated system privileges to use, and the assignment process is largely administrative.

According to the IANA registry, port 3591 is registered to LOCANIS G-TRACK Server, on both TCP and UDP.

What LOCANIS G-TRACK Is

Locanis is a German company that builds warehouse management and optimization software. Their systems use real-time location system (RTLS) technology — tracking forklifts, pallets, and workers as they move through a facility, then using that data to optimize task routing and equipment assignment.

G-TRACK appears to be their asset-tracking server component. The registration in IANA suggests the server communicated on port 3591, likely handling location data streams from hardware tags and transponders in the warehouse.

There is almost no public documentation about G-TRACK specifically. Locanis has since shifted its public focus to its SO360 (Site Optimizer 360) platform. G-TRACK, if it still exists, operates in deeply enterprise territory — the kind of software that runs in logistics centers and never appears in a public changelog.

A Ghost Registration

This is the honest situation: port 3591 is technically claimed, practically abandoned.

The IANA registration process doesn't expire. A company registers a port, ships a product, and then — if the product changes names, gets discontinued, or the company pivots — the port number stays in the registry forever. There's no cleanup. There's no reclamation.

Port 3591 is registered. Locanis still exists. But the specific product tied to this port has essentially vanished from public view, leaving the port in a state that is neither truly assigned nor truly free.

In practice, that makes it available. If you run a service on 3591, you're unlikely to conflict with anyone. But you're also not going to find this port in a firewall ruleset, a container template, or a cloud provider's default allow list.

How to Check What's Using Port 3591

If you see traffic on this port and want to know the source:

On Linux/macOS:

# Show which process is listening on 3591
ss -tlnp | grep 3591

# Or with lsof
lsof -i :3591

On Windows:

# Show process using port 3591
netstat -ano | findstr :3591

# Then look up the PID
tasklist | findstr <PID>

If something is listening on port 3591 and you didn't put it there, it's worth investigating — not because G-TRACK is a threat, but because unexpected open ports almost always are.

Why Unassigned Ports Matter

The 65,535 ports available to TCP and UDP aren't infinite. But they're vast enough that most of the registered range functions as unclaimed wilderness. Developers pick ports for their applications, sometimes checking IANA and sometimes not. The result is a registry full of legitimate assignments, obsolete registrations, and gaps where no one has bothered to stake a claim.

Port 3591 is in that gap — technically occupied by a product that predates the cloud era, registered by a company that's still operating but has moved on. It's not dangerous. It's not blocked. It's just... there.