Port 10087: Unassigned — A Port Without a Name

What Is Port 10087?

Port 10087 is a registered but unassigned port. It lives in the range 1024–49151, which is where IANA allocates ports for specific applications—but 10087 itself has no official entry in the registry. ¹

This doesn't mean the port sits empty. It means it has no standardized service name, no RFC defining its purpose, no canonical use case. It exists in a state of administrative indifference.

The Port Ranges Explained

The Internet's port system divides responsibility into three zones:

• Well-Known Ports (0–1023): Reserved for critical services. SSH, HTTP, SMTP live here. Assignment is highly controlled.
• Registered Ports (1024–49151): Available for applications to claim. An organization can register a port here with IANA, creating an official record.
• Dynamic/Ephemeral Ports (49152–65535): Temporary ports assigned on the fly. Nothing is registered; anything goes.

Port 10087 sits in the registered zone but has never been officially claimed. ²

Known Unofficial Uses

The most documented use comes from Veritas NetBackup PureDisk. ³ UDP port 10087 serves as a communication channel for the storage pool authority node, enabling disaster recovery functionality. This is a proprietary assignment—Veritas never registered it with IANA, but their software consistently listens on it.

Beyond that, 10087 is mostly silence. No major application has staked an official claim.

How to Check What's Listening on Port 10087

If you suspect something is using this port on your system:

On macOS/Linux:

lsof -i :10087
netstat -tuln | grep 10087

On Windows:

netstat -ano | findstr :10087

To check if it's open to the network:

nc -zv localhost 10087

Why Unassigned Ports Matter

Unassigned ports represent the Internet's pragmatism. IANA can't predict every application that will need a port. If you're building enterprise software and you need a reliable communication channel, you have options:

1. Register with IANA — Slow, formal, creates a permanent record
2. Use an ephemeral port — Dynamic, works for client connections, not for listening services
3. Pick an unassigned port in the registered range — Fast, unofficial, but stable if you're consistent

Most enterprise applications choose option 3. Veritas did. So did countless others. Port 10087 is quiet precisely because it's perfect for companies that don't need permission.

The unassigned ports are where the Internet actually works.