Port 188 (TCP/UDP) is officially assigned by IANA to mumps — specifically "Plus Five's MUMPS," a network protocol for a database language you've probably never heard of but have almost certainly depended on.1
What Is MUMPS?
MUMPS (Massachusetts General Hospital Utility Multi-Programming System) was created in 1966-1967 at Massachusetts General Hospital to manage patient medical records and laboratory information systems.2 It's a programming language and database system rolled into one—no separate database server needed, no schema required. Data is stored in sparse multidimensional arrays organized as balanced trees.3
MUMPS sounds archaic because it is. But it's also everywhere.
Where MUMPS Lives Today
The entire VA hospital system in the United States runs on VistA (Veterans Health Information Systems and Technology Architecture)—a massive suite of 80+ software modules built on MUMPS that manages electronic health records for 8 million veterans across 163 hospitals, 800+ clinics, and 135 nursing homes.2 The Indian Health Service uses it. Major parts of the Department of Defense hospital system use it.
Epic Systems, which dominates the electronic medical records market in the United States, is built on InterSystems MUMPS (now called M).2 If you've been to a hospital in America, there's a good chance your medical records touched a MUMPS database.
What Port 188 Was For
Port 188 was assigned to Plus Five's MUMPS—a specific implementation that used this port for network communication between MUMPS database nodes.1 The contact person listed in the IANA registry is "Hokey_Stenn."
In the 1980s, several vendors brought ANSI-standard MUMPS platforms to market with network capabilities.4 GT.M (another MUMPS implementation) pioneered logical multi-site application configurations that allowed MUMPS databases to span geography—years before major commercial databases offered similar features.4 Plus Five appears to have been one of these vendors, using port 188 for its distributed MUMPS protocol.
The Ghost Port
Here's the strange part: port 188 is officially registered, but you'll rarely see it in active use today. Plus Five as a company has faded into history. The port remains in the IANA registry like a gravestone—evidence that someone once built something here.
MUMPS implementations still exist and thrive, but they've moved on. Modern MUMPS systems use different protocols, different ports, or encapsulate their traffic in standard protocols like HTTP. The original network protocol that needed port 188 is likely obsolete.
Why This Matters
Port 188 is a reminder of how infrastructure ages on the Internet. Ports outlive the companies that registered them. The protocols change, but the port numbers persist in the registry forever—or until IANA explicitly reclaims them, which rarely happens.
Somewhere in the well-known ports range (0-1023), reserved for the most important Internet services, sits port 188: officially assigned to a healthcare database protocol from a vendor that no longer exists, for a language invented in 1966 that still runs hospitals today.
Checking Port 188
To see if anything is listening on port 188 on your system:
Linux/Mac:
Windows:
You probably won't find anything. And that's fine. Port 188 is assigned, registered, and waiting—just in case Plus Five's MUMPS ever comes back.
Related Ports
Port 188 sits in the well-known ports range alongside other database and healthcare-related protocols, though few are as obscure or as historically significant to medical infrastructure.
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