Port 2476: Unassigned — A registered port with no tenant

What Port 2476 Is

Port 2476 is unassigned. IANA — the Internet Assigned Numbers Authority, which maintains the official registry of port numbers — has no service name, no protocol, and no RFC associated with this port.¹

That's not unusual. The registered port range (1024–49151) contains thousands of unassigned ports. Most will stay that way. Port numbers only get assigned when someone formally registers a service and IANA approves it. Port 2476 has never been through that process.

What Range It Belongs To

Port 2476 falls in the registered ports range: 1024–49151.

Here's what that range means in practice:

• Well-known ports (0–1023): Reserved for fundamental Internet services. HTTP lives at 80, HTTPS at 443, SSH at 22. These require elevated privileges to bind on most operating systems.
• Registered ports (1024–49151): Anyone can request registration from IANA for a specific application. Many are assigned; many are not. No special privileges required to bind.
• Dynamic/ephemeral ports (49152–65535): Used temporarily by clients for outbound connections. Not assigned to services.

Within the registered range, an unassigned port like 2476 is fair game. Any application can use it without coordination. Nothing is expected to be there.

Known Unofficial Uses

Port 2476 has no documented legitimate application associated with it. It appears in several older security databases as a port historically observed in use by malware — specifically, trojan-style remote access tools that needed a port to call home.²

This is worth understanding clearly: malware often chooses unassigned ports on purpose. An assigned port carries expectations. Traffic on port 443 should look like HTTPS. Traffic on port 25 should look like SMTP. Unassigned ports have no such baseline, which makes anomalous traffic harder to detect at a glance.

There is no evidence that any current, widespread application uses port 2476. If you see it open on a system you didn't configure, that's worth investigating.

How to Check What's Listening

On any system, you can see what process is holding a port open:

Linux / macOS:

# Show what's listening on port 2476
ss -tlnp sport = :2476

# Alternative with lsof
lsof -i :2476

# Quick netstat approach
netstat -tlnp | grep 2476

Windows:

# Show listening ports with process IDs
netstat -ano | findstr :2476

# Then look up the process ID
tasklist /FI "PID eq <PID>"

macOS (modern):

lsof -nP -iTCP:2476 -sTCP:LISTEN

If nothing returns, nothing is listening. If something returns, the process name and PID tell you exactly what it is.

Why Unassigned Ports Matter

The port registry is a coordination system, not an enforcement mechanism. Nothing stops software from using any port it wants. The registry just helps everyone agree on where to find things.

Unassigned ports represent the gaps in that coordination — spaces where convention hasn't yet spoken. Most are simply empty: no service claimed them, no traffic flows through them. But precisely because they're quiet, they're useful to anyone who wants to operate without drawing attention.

Monitoring for unexpected activity on unassigned registered ports is a legitimate part of network security. A system quietly accepting connections on port 2476 with no record of you setting that up is exactly the kind of signal worth following.