Port 1676: Netcomm1/Netcomm2 — A Registered Name Nobody Recognizes

Port 1676 sits in the registered port range and carries two IANA-assigned names: netcomm1 (TCP) and netcomm2 (UDP). Those names are where the trail ends. No RFC defines these protocols. No major software claims them. No vendor documentation explains what they were meant to do.

This is not unusual. The registered port range is full of names like this — claimed at some point by some organization, never deployed at scale, and now quietly occupying space in a database.

The Registered Port Range

Ports 1024 through 49151 are the registered ports. Unlike the well-known ports below 1024 (which require root privileges to bind on Unix systems and carry protocols like HTTP and SSH), registered ports are available to any application without elevated permissions.

The intent was to give software vendors a stable, unambiguous address. Register your port number with IANA, and you can tell your users "our software listens on port 1676" without colliding with something else. In practice, registration is often informal and the documentation sparse — which is how you end up with "netcomm1" in the registry and nothing else.

What's Actually on This Port

Honest answer: unknown. Port databases list the netcomm1/netcomm2 names, and the SANS Internet Storm Center observes occasional scanning activity on port 1676 — meaning automated tools are probing it regularly, looking for something to respond.¹ Whether that's opportunistic scanning of the entire port range or targeted probing for a specific service, the data doesn't say.

If you find this port open on a system you manage, the safe assumption is that something custom is using it. Check what's listening before assuming it's benign.

How to Check What's Listening on This Port

On Linux or macOS:

# Show the process listening on port 1676
sudo lsof -i :1676

# Or with ss (Linux)
sudo ss -tlnp sport = :1676

On Windows:

# Show all listening ports with process IDs
netstat -ano | findstr :1676

# Then match the PID to a process
tasklist | findstr <PID>

If nothing is listening, the port is closed — normal. If something is, identify the process before deciding whether it belongs there.

Why Unassigned-in-Practice Ports Matter

The gap between "registered" and "documented" is where problems hide. A port with a name but no known protocol is harder to reason about in firewall rules and security audits. You can't look it up and immediately know whether to allow or block it.

This is one reason security teams default to blocking all ports not explicitly required — the alternative is maintaining a mental model of 48,000 registered ports, many of which have no more documentation than netcomm1 does.