Port 1040 — The Unassigned Registered Port

What This Port Is

Port 1040 is an unassigned port in the registered range (1024–49151). That means IANA has never officially allocated it to any standardized protocol or service. It's available for anyone to request, but no one has.

The Port Range

Port 1040 falls in the middle of the registered ports—the space reserved for user applications and services that want official IANA registration.¹ This range exists specifically to prevent conflicts: if your application uses a registered port, IANA guarantees no other standards-track protocol will claim it.

Known Unofficial Use

netsaint_statd — A Perl daemon from the Netsaint project (the predecessor to Nagios) used port 1040 as its default listening port for remote host monitoring.² Netsaint itself is no longer maintained, but legacy installations may still have netsaint_statd listening on this port. The daemon collected status information from monitored systems and reported back to the central Netsaint server.

If you see port 1040 open on an older infrastructure monitoring system, this is likely what you've found.

How to Check What's Listening

To see if anything is actually listening on port 1040:

On Linux/macOS:

# Show listening ports
netstat -tulpn | grep 1040

# Or with ss (newer systems)
ss -tulpn | grep 1040

# Or with lsof
lsof -i :1040

On Windows:

netstat -ano | findstr :1040

Why Unassigned Ports Matter

Most people think of the Internet as a system of well-known, registered services: HTTP on 80, SMTP on 25, SSH on 22. The registered-but-unassigned ports reveal something else—the Internet also runs on improvisation. Custom applications, internal monitoring tools, proprietary protocols, experimental services. These ports are the infrastructure nobody sees because they're not in any standard.

If port 1040 is listening on your network, you need to know what put it there. It won't be in any RFC. Someone chose it. Ask why.