Port 2373: Remograph License Manager — The floating license server for a niche 3D tool

What Port 2373 Does

Port 2373 is assigned to remographlm — the network license manager for Remo 3D, a 3D scene modeling and visual simulation tool made by Remograph, a Swedish software company.

The service runs as a floating license server. When an organization buys a network license for Remo 3D rather than a per-machine license, the license manager runs on a central server and hands out license tokens to clients on demand. Connect to the license server, get a token, use the software. Disconnect, and the token returns to the pool.

Port 2373 TCP is the address where clients knock to check out those tokens.

Protocol: TCP (assigned) UDP: Reserved but not used IANA registration date: January 21, 2009 Registrant: Per Fahlberg

The Port Range It Lives In

Port 2373 falls in the registered ports range (1024–49151). These ports are not reserved for well-known system services the way ports below 1024 are, but they are tracked by IANA. Any company or developer can apply to register a port for their application — and Remograph did exactly that in 2009.

Registration means IANA officially records that this port is associated with remographlm. It does not mean the port is blocked or restricted. It means that if you see port 2373 in use and wonder "what is that?", you have an authoritative answer.

Is It Dangerous?

No. Remograph's license manager is legitimate software used by engineers and visualization professionals running Remo 3D. It is not associated with malware or known exploits.

That said, any open port is an attack surface. If you see port 2373 listening on a machine that has no reason to run Remo 3D licensing software, investigate it. Unexpected open ports are always worth questioning — not because this one is suspicious, but because all unexpected open ports are.

How to Check What's Listening on This Port

Linux and macOS:

# Show what process is listening on port 2373
lsof -i :2373

# Alternative using ss
ss -tlpn | grep 2373

Windows:

netstat -ano | findstr :2373

The output will show the process ID (PID). You can then look up that PID in Task Manager or with tasklist to confirm it is the Remograph license manager — or find out what else might be using it.

Why Unassigned-Looking Ports Matter

Most registered ports are invisible to most people. You will never knowingly encounter remographlm unless you work with Remo 3D. But the system of registration exists for a reason: it prevents chaos.

Without port registration, two applications might independently choose the same port and conflict. Without the registry, a network administrator seeing port 2373 open would have no starting point for investigation. The IANA registry is the phone book of the port world — you rarely use it, but you are glad it exists when you need it.

Port 2373 is a small example of this system working correctly: a niche application, registered properly, quietly serving its purpose on the networks where it belongs.