Port 3726: Xyratex Array Manager — A registered ghost

What Port 3726 Is

Port 3726 is registered to Xyratex Array Manager (service name: array-manager), filed with IANA in April 2003 on both TCP and UDP by David A. Lethe at Xyratex.¹

Xyratex was a British storage hardware company that made RAID disk arrays for enterprise customers. Their StorView management software let administrators configure and monitor those arrays remotely over a network. Port 3726 was how the Array Manager component communicated.

Seagate acquired Xyratex in 2014.² The port registration remains in the IANA database. The original software is long past end-of-life.

What That Registration Means

The registered port range runs from 1024 to 49151. Unlike well-known ports (0–1023), registered ports don't require root/administrator privileges to bind. Any application can claim one — you don't need permission from the OS, only from IANA if you want an official assignment.

Registered ports are first-come, first-served. Xyratex filed paperwork in 2003, got their number, and port 3726 became theirs forever. IANA doesn't reclaim registrations when companies are acquired or dissolved. The registry accumulates — it doesn't clean house.

This means port 3726 is unlikely to show up on any modern system doing anything official. If something is listening on it, it's either legacy Xyratex/StorView infrastructure (rare) or something using the port informally, which anything is free to do.

Checking What's Listening on This Port

If you see traffic on port 3726 and want to know the source:

macOS / Linux:

# See what process is using port 3726
sudo lsof -i :3726

# Or with ss (Linux)
ss -tlnp | grep 3726

Windows:

netstat -ano | findstr :3726

The process ID from these commands will tell you what's actually running.

Why Ghost Registrations Exist

IANA assigns port numbers to prevent collisions between applications that want to use the same port. The system works well when everyone registers — two applications fighting over the same port causes chaos.

But companies get acquired. Products get discontinued. The registrations stay. Port 3726 is one of hundreds of registered ports pointing at software that no longer ships, maintained by organizations that no longer exist as independent entities.

This isn't a flaw — it's the cost of permanence. The alternative, a registry that expires and reassigns old numbers, would break any long-running legacy system still using the original assignment. So the database grows, ghost registrations accumulate, and port 3726 waits in the registry, registered to a company that Seagate now owns.