Port 1764: Unassigned — the upper edge of KDE Connect's range

What Range This Port Belongs To

Port 1764 sits in the registered ports range (1024-49151). IANA maintains this range for services that have formally requested a port assignment. Unlike the well-known ports (0-1023), registered ports don't require root or administrator privileges to open, and unlike ephemeral ports (49152-65535), they're meant to be stable, predictable addresses for specific services.

Port 1764 has no IANA-assigned service. IANA lists it as unassigned.¹

Unofficial Use: KDE Connect

In practice, port 1764 appears most often as the upper boundary of KDE Connect's dynamic port range (1714-1764).

KDE Connect is the software that lets your Android phone and your Linux desktop talk to each other — sharing clipboard contents, sending files, forwarding notifications, using your phone as a trackpad. To do this, KDE Connect needs to discover devices on the local network and then establish connections to transfer data.

It claims the entire range 1714-1764 for both TCP and UDP:

• UDP broadcasts on ports in this range announce devices to each other ("I'm here, can anyone hear me?")
• TCP connections on ports in this range carry the actual data — files, notifications, commands

Port 1764 isn't functionally special within KDE Connect. It's simply where the range ends. If you're configuring a firewall and see port 1764 in the rules, you're almost certainly looking at a KDE Connect or GSConnect (the GNOME equivalent) configuration.²

How to Check What's Listening

If port 1764 is open on a machine you control and you want to know why:

# On Linux/macOS — show which process owns port 1764
sudo ss -tlnp | grep 1764
sudo lsof -i :1764

# On Windows
netstat -ano | findstr :1764

The output will show you the process ID (PID) and let you identify what's actually using the port.

Why Unassigned Ports Matter

The registered range exists as a coordination layer. When a developer assigns a service to a random port, users and administrators have no way to know what that port does without documentation. IANA assignment provides a lookup table: port 1764 should mean something specific and consistent across every machine on the Internet.

When ports go unassigned — or when software claims port ranges without registration (as KDE Connect does) — that coordination breaks down. A firewall rule opening 1714-1764 is ambiguous. Is it KDE Connect? Something else? The only way to know is to check the machine directly.

Port 1764 is a small example of the broader reality: IANA's registry covers the theory. What actually runs on any given port is a different question entirely.