Port 1805: Unassigned — An Empty Slot in the Registered Range

Port 1805 has no officially assigned service. IANA, the organization that manages port assignments, has not allocated this port to any protocol or application.¹

What Range It Belongs To

Port 1805 falls in the registered ports range: 1024 through 49151.

This range is the middle tier of the port numbering system. Below it are the well-known ports (0-1023), where the foundational protocols live — HTTP at 80, HTTPS at 443, SSH at 22. Those require elevated system privileges to bind on most operating systems. Above the registered range are the ephemeral ports (49152-65535), the temporary numbers your OS hands out to outgoing connections that need a return address.

The registered range was designed for applications to stake a claim — submit a request to IANA, get a number, publish it so your protocol has a known home. Port 1805 was never claimed.

Known Unofficial Uses

None documented. Port 1805 does not appear in common threat intelligence databases as a malware signature, is not associated with any notable peer-to-peer application, game, or enterprise software, and shows no meaningful pattern in network traffic analyses.

This is not unusual. The registered range has 48,128 slots. Many sit empty.

If Something Is Listening Here

If you scan your system and find a process bound to port 1805, it is using the port by private convention — configured specifically for that machine or network, not following any public standard.

To check what is listening:

Linux/macOS:

ss -tlnp | grep 1805
# or
lsof -i :1805

Windows:

netstat -ano | findstr :1805
# Find the process by PID:
tasklist | findstr <PID>

If you find something and don't recognize it, check the process name against what you have installed. Unrecognized listeners on arbitrary ports are worth investigating.

Why Unassigned Ports Matter

The port numbering system only works because most applications follow conventions. When a service claims a well-known port and registers it, every firewall, every network monitor, every engineer in the world knows what to expect there.

Unassigned ports like 1805 are the gaps in that agreement. They are not dangerous by definition — private applications use them constantly, and legitimately. But they carry less trust than a registered port, because there is no public record of what should be there.

A listener on port 443 is almost certainly TLS traffic. A listener on port 1805 is whatever someone decided to put there.