Port 570: Unassigned — Where eMule Built a Home

Port 570 sits in the well-known port range (0-1023), the space IANA reserves for system services and standardized protocols. But if you check the official registry, you'll find nothing assigned here. Port 570 is officially unassigned.

That didn't stop eMule from using it.

What Lives Here (Unofficially)

eMule, a peer-to-peer file sharing client popular in the 2000s, claimed port 570 for itself.¹ The application uses both protocols:

TCP on port 570 — Establishes stable connections between eMule clients for file transfers. Connection-oriented, reliable, ensures data arrives in order.

UDP on port 570 — Enables faster data transfer between peers. Connectionless, no guarantees, but lower overhead when you don't need reliability.

eMule never asked IANA for permission. It just started using the port. This is the messy reality of how the Internet actually works.

The Well-Known Range

Ports 0-1023 are called "well-known ports" or "system ports." IANA assigns them to standardized services—HTTP on 80, HTTPS on 443, SSH on 22. Operating systems typically require root or administrator privileges to bind to these ports, which is meant to prevent random applications from impersonating important services.

Port 570 is in this privileged range. But it has no official assignment. It's reserved space that no one formally claimed.

Why Unassigned Ports Matter

The Internet has 65,535 ports per protocol (TCP and UDP). Not all of them need assignments. Unassigned ports serve several purposes:

Room for future standards — New protocols need port numbers. Unassigned ports provide space for innovation.

Unofficial experimentation — Applications can use unassigned ports for testing, internal services, or (like eMule) just because they need a port and this one looked available.

The gap between theory and practice — IANA maintains the official registry, but actual network traffic doesn't always align with it. Applications use whatever ports work. Port 570 is a reminder that official assignments and real-world usage are different things.

Security Considerations

Even though port 570 has no official assignment, if something is listening on it, that something matters. eMule opens it for peer-to-peer file sharing, which has implications:

Firewall rules — Some ISPs or network administrators block well-known ports by default, especially ones associated with file sharing.

What's actually listening — Just because port 570 is "supposed to be" eMule doesn't mean it is. Any application can bind to any port. If you see traffic on 570, verify what's actually using it.

P2P security model — eMule connects you directly to strangers on the Internet. That's the whole point of peer-to-peer. But it also means your machine is accepting connections from unknown sources.

How to Check What's Listening

On Unix-like systems (Linux, macOS):

# See what's listening on port 570
sudo lsof -i :570

# Or using netstat
sudo netstat -tuln | grep :570

On Windows:

# Show active connections and listening ports
netstat -ano | findstr :570

If something is listening, the output will show the process ID. You can verify what application owns that process.

The Honest Truth

Port 570 demonstrates that the Internet's port system isn't as neat as the registry suggests. IANA maintains official assignments. Applications do what they want. The two overlap most of the time, but not always.

eMule claimed port 570 without permission and used it for years. That's not vandalism—it's just how things work when you're building a distributed system with no central authority beyond voluntary registries.

Unassigned ports aren't useless. They're the space between what's standardized and what's possible. Port 570 is officially no one's. Unofficially, it belonged to anyone willing to use it.