Port 3487: Unassigned — Available Territory in the Registered Range

What Range This Port Belongs To

Port 3487 is a registered port — part of the range from 1024 to 49151. This range sits between the well-known ports (0–1023), which are reserved for fundamental Internet services, and the ephemeral ports (49152–65535), which operating systems assign temporarily to outgoing connections.

Registered ports can be formally claimed through IANA, the organization that manages port assignments. Port 3487 has not been claimed. It appears in the IANA registry with no service name and no assigned protocol.¹

That's not unusual. The registered range contains 48,128 possible ports, and hundreds of them sit unassigned — available territory that applications can use without official registration, though without a guarantee that nothing else will collide with them.

Known Unofficial Uses

One documented use appears in ClearOne's Converge Pro / Converge SR audio conferencing product line. The management console software uses port 3487 for local network discovery — scanning for Converge hardware units connected to the same network. If port 3487 is blocked by a firewall, the console cannot detect units, and the Ethernet device selection dropdown shows nothing.²

This is a common pattern for unassigned ports: a hardware vendor or software product picks a number, uses it for internal management traffic, and never registers it formally. It works until something else decides to use the same number.

No other significant unofficial uses for port 3487 appear in public documentation or threat intelligence databases.

How to Check What's Listening on This Port

If port 3487 is open on a machine you manage, these commands will tell you what process owns it:

macOS / Linux:

sudo lsof -i :3487

or

sudo ss -tlnp | grep 3487

Windows:

netstat -ano | findstr :3487

Then cross-reference the PID with Task Manager or:

tasklist /FI "PID eq <PID>"

If something unexpected is listening, treat it as a signal worth investigating. Unassigned ports are sometimes used by malware precisely because they're unlikely to be monitored.

Why Unassigned Ports Matter

The port system works because of shared conventions. When a service registers a port, every firewall administrator, every network engineer, every security scanner knows what to expect there. Port 443 carries HTTPS. Port 22 carries SSH. The assignment creates a shared language.

Unassigned ports don't have that language. Something listening on port 3487 could be legitimate management software, a developer's test service, or something that shouldn't be there at all. The port number alone tells you nothing — you have to look.

That's the honest answer about unassigned ports: they're not mysterious, they're just uninscribed. The port does whatever the software using it decides.