Port 2110: UMSP — The Forgotten Memory Space

What This Port Is

Port 2110 is a registered port — sitting in the range from 1024 to 49151, where the Internet Assigned Numbers Authority (IANA) tracks assignments for specific services and protocols.

Its assigned protocol is UMSP: Unified Memory Space Protocol, defined in RFC 3018, published in December 2000.¹

What UMSP Was Trying to Do

UMSP was an ambitious idea. Instead of sending messages between computers — the way almost every networked application works — UMSP proposed something different: give every networked node a shared 128-bit address space, so programs could simply read and write remote memory as if it were local.

Distributed computing, without the distributed complexity. Write to an address. Another machine sees the change. No explicit message passing required.

The protocol organized computation into a three-level hierarchy: jobs (user applications), tasks (instances of a job running on individual nodes), and control threads. A designated Job Control Point managed resource allocation across the cluster to prevent the pointer inconsistencies that would otherwise make shared distributed memory chaotic.

TCP carried the interactive communication. UDP handled fire-and-forget instructions that didn't need acknowledgment.

Why You've Never Heard of It

RFC 3018 is classified as Experimental — not a standard, not even a proposed standard. The IETF explicitly notes it carries "no formal standing in the IETF standards process."¹ It was one person's or team's idea, published for the record, never endorsed, never implemented at scale.

The year 2000 was full of ideas like this — distributed shared memory, virtual machines running across networks, unified address spaces. Most of them lost to simpler approaches: message queues, HTTP APIs, eventually the cloud abstractions we use today.

UMSP was a road not taken. Port 2110 is the empty lot where it would have been.

What's Actually on Port 2110 Today

Probably nothing, on most machines. Some port databases mention it in connection with gaming servers (DayZ has been cited), but DayZ's actual standard ports are 2302 UDP and 27016 UDP — port 2110 isn't in DayZ's official configuration.²

If something is listening on port 2110 on your machine, it's worth knowing what it is.

How to Check What's Listening

On Linux or macOS:

# Show what process is using port 2110
sudo lsof -i :2110

# Or with ss (modern Linux)
ss -tlnp | grep 2110

On Windows:

netstat -ano | findstr :2110

The output will show the process ID. Cross-reference with Task Manager or tasklist to identify the application.

Why Unassigned Ports Matter

The registered port range (1024–49151) exists so that applications can claim a consistent home. Port 80 is always HTTP. Port 443 is always HTTPS. The predictability makes firewalls possible, makes network monitoring coherent, makes the Internet navigable.

When a port is assigned but abandoned — as UMSP effectively is — it becomes available for unofficial use by convention, even if IANA's records still show the old assignment. The system isn't perfectly clean. It's more like a city where old storefronts get repurposed without anyone updating the zoning maps.

Port 2110 is one of thousands of registered ports carrying the ghost of an idea that didn't survive contact with reality.