Port 806 — Unassigned

Port 806 sits in the well-known ports range (0-1023), but it has no official assignment. IANA reserves it, along with ports 803 through 809, but no protocol has ever claimed this address.¹

What "Unassigned" Means

The well-known ports range is carefully controlled by IANA. Every assignment requires documentation, a protocol specification, and approval. Port 806 passed through this system and remained unclaimed.

Unlike dynamic ports (49152-65535), which any application can use temporarily, port 806 is reserved. It cannot be used without IANA approval. It waits—officially held but officially empty.

Why Unassigned Ports Exist

Not every port number has a service. Some ranges remain unassigned for future use. Some were assigned to protocols that died. Some, like port 806, were simply never needed.

The well-known range has 1,024 ports (0-1023). Many are assigned to foundational protocols: HTTP, HTTPS, SSH, DNS, SMTP. But not all. Port 806 is one of the gaps.

The Neighborhood: Ports 803-809

Port 806 is part of a seven-port block that IANA has kept unassigned:¹

• Port 803 — Unassigned
• Port 804 — Unassigned
• Port 805 — Unassigned
• Port 806 — Unassigned
• Port 807 — Unassigned
• Port 808 — Unassigned
• Port 809 — Unassigned

This is unusual. Most of the well-known range is densely allocated. Finding a seven-port stretch with no assignments is rare. It suggests this block was reserved for something that never materialized.

Checking What's Listening

Even though port 806 has no official assignment, something could still be listening on it—either a custom application or malware. To check what's using port 806 on your system:

On Linux/Mac:

sudo lsof -i :806
sudo netstat -tuln | grep :806

On Windows:

netstat -ano | findstr :806

If you see output, something is bound to port 806. It's not an official service—it's something specific to your system.

Security Considerations

Unassigned ports should be quiet. If you see traffic on port 806, investigate:

• Legitimate custom applications might use it for internal communication
• Malware sometimes uses uncommon ports to avoid detection
• Misconfigurations can bind services to unexpected ports

The SANS Internet Storm Center tracks attack activity across all ports, including port 806.² While unassigned ports typically see little traffic, they're not immune to scanning or exploitation attempts.

Related Ports

Nearby assigned ports:

• Port 800 — Unassigned (another gap)
• Port 801 — Unassigned
• Port 802 — Unassigned

The entire 800-809 range is remarkably empty. Most well-known ports below 800 have assignments. Most above 810 do too. This is a quiet stretch.