Port 2574: Blockade BPSP — A Name Without a Story

What Port 2574 Is

Port 2574 sits in the registered ports range (1024–49151). These are ports that organizations and developers can formally claim with IANA — the Internet Assigned Numbers Authority — to reserve a port for their protocol or application.

IANA's registry lists port 2574 as "blockade-bpsp" on both TCP and UDP. That name appears across port databases, security scanners, and firewall reference lists. What it doesn't appear in: any RFC, any official specification, any vendor documentation, or any meaningful technical source that explains what "Blockade BPSP" actually is or does.

It's a name in a registry with no story attached.

The BPSP Confusion

A GitHub project exists for something called BPSP — Basic Publish Subscribe Protocol — a lightweight pub/sub messaging system with topic-based routing, wildcards, and broker-client architecture. It's an interesting protocol. It is almost certainly unrelated to whatever "blockade-bpsp" refers to. The GitHub project has no connection to port 2574 or to any entity named "Blockade."¹

Security History

Some security databases flag port 2574 as having been used by malware at some point — a trojan that chose this quiet, obscure port precisely because nothing legitimate was listening on it. That's a common pattern: attackers pick unoccupied registered ports to blend into normal port noise.

There is no currently active malware specifically associated with this port. If you see unexpected traffic on 2574, it warrants investigation, but it is not inherently a red flag on its own.

How to Check What's Listening

If port 2574 is active on your system or network, these commands will tell you what process owns it:

Linux / macOS:

# Show what's listening on port 2574
ss -tlnp | grep 2574

# Or with lsof
lsof -i :2574

Windows:

netstat -ano | findstr :2574

The output will include the process ID (PID). Cross-reference that PID in Task Manager or with ps aux | grep <PID> to identify the application.

Why Unassigned Ports Exist

The registered port range has over 48,000 slots. Many were claimed years ago by companies or developers who never deployed anything, abandoned projects after the reservation, or built internal tools that never saw public documentation. The IANA registry is not self-cleaning — a name registered in 1998 for a product that never shipped still occupies its spot today.

This is the likely story of port 2574: someone registered it, named it, and then nothing came of it. The reservation outlasted whatever it was meant for.