Port 3722: Xserve RAID — Apple's Abandoned Storage Port

What This Port Is

Port 3722 falls in the registered ports range (1024–49151). These ports are assigned by IANA to specific services — or they sit unassigned, waiting.

This one was assigned. Once.

In March 2003, Apple registered port 3722 for Xserve RAID, their enterprise-grade storage array built for the Xserve server line. When Apple discontinued the Xserve RAID in 2008 and the Xserve itself in 2011, the product line disappeared. The port registration eventually went with it. IANA now lists port 3722 as unassigned on both TCP and UDP.¹

The Xserve RAID Era

The Xserve RAID was Apple's attempt to compete in data center storage. It ran from 2002 to 2008 and was genuinely used in media production, universities, and creative studios that were already Mac shops. Port 3722 carried communication between Xserve RAID units and the RAID Admin software used to manage them.

When the hardware died, the software died. When the software died, there was nothing left to listen on port 3722.

What You Might See Today

Scanning activity. SANS ISC logs consistent low-level probes against port 3722. Nothing alarming — threat level stays green — but scanners don't know (or care) that no one's home.² They're either running broad port sweeps or they're hunting for any surviving Xserve RAID installations still somehow running in 2026.

Custom or legacy applications. Developers and sysadmins sometimes reach for unassigned ports when they need a port. Port 3722 is unlikely to conflict with anything, which makes it marginally attractive for internal tools. If you're seeing unexpected traffic on this port on your network, it's worth investigating.

Nothing. Most of the time, on most machines, port 3722 is closed, unbound, and silent.

What's Listening on This Port?

To check what process, if any, is using port 3722 on your system:

macOS / Linux:

# Show what's listening on port 3722
sudo lsof -i :3722

# Or with ss (Linux):
sudo ss -tlnp sport = :3722

Windows:

netstat -ano | findstr :3722

If nothing comes back, nothing is listening. That's the expected result for a machine with no custom software using this port.

Why Unassigned Ports Matter

The port numbering system works because ports mean things. When software wants to talk HTTP, it goes to port 80. When it wants HTTPS, it goes to 443. The registry keeps those meanings stable across the entire Internet.

Unassigned ports are the gaps — the lots where a building once stood or was never built. They're not broken. They're just open space. Software can use them for internal purposes, but nothing on the public Internet has an expectation of finding a specific service there.

Port 3722 is a small illustration of how infrastructure outlives the products built on it. The Xserve RAID is long gone, but its port number is still in every port scan, still in network databases, still getting poked by bots that don't know the address is vacant.