Port 1931: AMD SCHED — A Registered Ghost

What This Port Is

Port 1931 sits in the registered port range (1024-49151). These are ports that vendors and developers claim with IANA to reserve space for their applications. Unlike the well-known ports below 1024, no special system privileges are required to open them.

IANA's registry lists port 1931 as belonging to a service called AMD SCHED (service name: amdsched), registered for both TCP and UDP. The registrant appears to have been AMD, presumably for some kind of scheduling or job-dispatch service.

But that's where the trail ends.

No RFC was published. No technical specification is publicly available. No documentation describes what AMD SCHED actually does, how it works, or whether it was ever deployed. Port 1931 is one of those registered entries where someone filed the paperwork and then the project either never shipped, shipped without using this port, or was abandoned before anyone wrote anything down.

Commonly Observed Uses

None documented. In practice, port 1931 is open only if something on your machine has bound to it, which would be application-specific rather than following any standard protocol.

Some older security databases flagged it as having been used by malware in the past. That's not unusual for unmonitored ports in the registered range; attackers sometimes pick quiet, officially registered ports precisely because they look legitimate in logs. There is no current evidence of active exploitation.

How to Check What's Using This Port

If you see port 1931 open on your system and aren't sure why, check which process owns it:

macOS / Linux:

sudo lsof -i :1931

Windows:

netstat -aon | findstr :1931

The output will show the process ID (PID). On macOS/Linux, cross-reference with ps aux | grep <PID>. On Windows, look up the PID in Task Manager.

If nothing is listening, the port is closed and there's nothing to worry about. If something unexpected is listening, that warrants investigation.

Why Unassigned (or Dormant) Ports Matter

The registered port range contains thousands of entries like this one: claimed, named, and then effectively abandoned. They aren't dangerous by themselves. But they serve as a reminder that the port numbering system is partly historical artifact. IANA's registry reflects who called dibs, not necessarily who built something that lasted.

This is also why "unassigned" doesn't mean "unused." Software can bind to any port it wants. The IANA registry is a coordination mechanism, not enforcement. Port 1931 could be running anything on any given machine, because nothing official is guarding that space.