Port 3069: ls3 — Powerware's Forgotten Power Protocol

What This Port Is

Port 3069 sits in the registered ports range (1024-49151). These are ports that individuals and organizations can register with IANA to reserve for their software. Registration doesn't mean the software is widespread — it means someone filed the paperwork.

IANA's records show port 3069 assigned to ls3, registered by Jim Thompson of Powerware, a company that made uninterruptible power supplies (UPS) and power management software. Powerware was acquired by Eaton in 2004, where it lives on as Eaton's power management division.¹

The ls3 Protocol

Almost nothing is publicly documented about ls3. What the IANA registry reveals:

• Port 3068 is registered as ls3bcast — ls3 Broadcast
• Port 3069 is registered as ls3 — the unicast counterpart

This pairing tells a familiar story: software broadcasts on 3068 to discover devices on the local network, and devices respond or communicate directly on 3069. It's the same pattern used by dozens of device management protocols — send a shout, get a reply.

The protocol was almost certainly part of Powerware's network management software stack, used by their UPS hardware to communicate status, load, battery health, and power events to management consoles. UPS network management was a serious concern in data centers — knowing your power was failing before your servers noticed was the difference between a graceful shutdown and a crash.

Is Anything Using This Port Today?

Unlikely in most environments. Powerware's proprietary management protocols have largely been superseded by standard approaches (SNMP, Modbus, vendor-neutral tools like Network UPS Tools). If you see traffic on port 3069, it's probably one of:

• Legacy Powerware/Eaton power management software still running somewhere
• An application that chose this port informally
• A misconfigured service

How to Check What's Listening

On Linux/macOS:

# Show what process is listening on port 3069
ss -tlnp | grep 3069

# Or with lsof
lsof -i :3069

On Windows:

# Show listening ports with process IDs
netstat -ano | findstr :3069

# Then look up the process
Get-Process -Id <PID>

If nothing is listening, that's normal. Most machines have no reason to run ls3.

Why Unassigned-in-Practice Ports Matter

The registered ports range contains thousands of ports like this one — names in a registry, tied to software that peaked in a specific decade, registered by engineers at companies that no longer exist under that name. They're not wasted space. They're a fossil record.

When a security scanner flags unexpected traffic on port 3069, knowing it was once Powerware's UPS protocol narrows the investigation. When a firewall rule mentions it, now you know why it exists. The registry is a library of institutional memory — mostly unread, occasionally essential.