Port 1679: darcorp-lm — The Aerospace Footnote

Port 1679 sits in the registered port range, formally claimed by IANA, carrying a name most people have never heard: darcorp-lm.

What "Registered" Means

The port numbering system has three tiers:

• Well-known ports (0-1023): Assigned to foundational Internet protocols — HTTP, HTTPS, DNS, SSH. These are the ports the Internet runs on.
• Registered ports (1024-49151): Claimed by software vendors and organizations for specific applications. IANA records the claim, but these ports are not policed. Anyone can use them.
• Dynamic/ephemeral ports (49152-65535): Temporarily assigned by operating systems for outbound connections. No permanent assignments.

Port 1679 lives in the middle tier. It has a name on file with IANA, but that name means nothing to your firewall or anyone else's router.

The Registration: darcorp-lm

IANA lists port 1679 as darcorp-lm, both TCP and UDP — the license manager for DARcorporation (Design, Analysis and Research Corporation), a small aerospace engineering firm based in Lawrence, Kansas.¹

DARcorporation makes engineering software for aircraft design and aerodynamic analysis, including a tool called FlightStream — a surface-vorticity panel-method flow solver used to model airflow over aircraft surfaces.² Like most commercial engineering software, it requires a license manager to handle seat allocation across a network. Port 1679 is what that license manager listens on.

The total population of people who have ever interacted with this port intentionally is probably measured in hundreds: engineers at aerospace companies and research institutions running floating licenses for niche simulation software.

What This Port Looks Like in Practice

If you're not running DARcorporation software, port 1679 should be closed on your systems. If something is listening there unexpectedly, it warrants investigation.

To check what's using port 1679 on your machine:

Linux/macOS:

# Show what process is listening on port 1679
sudo ss -tlnp | grep 1679
# or
sudo lsof -i :1679

Windows:

netstat -ano | findstr :1679

If you find a process, check its name against your installed software. An unknown process on an unexpected port is worth investigating.

Why Unassigned-in-Practice Ports Matter

The IANA registry has thousands of entries like this: formally claimed, rarely deployed, invisible to almost everyone. This matters for two reasons.

First, the registration exists to prevent collisions. If DARcorporation picked port 1679 and registered it, other software vendors know not to claim it. The system works through coordination, not enforcement.

Second, gaps in the registry are attack surface. Ports without active services are quiet — but quiet ports can be hijacked. Malware and unauthorized services sometimes open listening sockets on registered-but-unused ports precisely because nobody is watching them closely.

A closed port is safe. A port that's open when it shouldn't be is worth understanding.