Port 1376 holds a reservation for a program that barely exists in modern memory.
What Lives Here
According to IANA's official registry, port 1376 is assigned to IBM Person to Person Software (service name: ibm-pps)1. The assignment covers both TCP and UDP protocols. That's what the registry says.
What the registry doesn't say: what this software actually did, when it was discontinued, or whether a single instance of it still runs anywhere on the Internet today.
The Software That Was
IBM Person to Person Software appears to have been a collaboration or communication tool from IBM's portfolio, likely from the 1990s. The evidence for its existence is thin—a port assignment, a few entries in port databases, and not much else.
No user manuals surface in searches. No screenshots. No nostalgic forum posts from people who remember using it. The software vanished, but its port number remains, officially registered, waiting for traffic that will never arrive.
Why This Port Still Exists
When IANA assigns a port number, it doesn't typically reclaim it when the software dies. The registry is append-only in spirit. Once registered, a port stays registered, even if the protocol becomes extinct.
There's no real cost to leaving it assigned. The registered port range (1024-49151) contains over 48,000 possible ports. Plenty of room for both the living and the dead.
What the Registered Range Means
Port 1376 falls in the registered ports range (1024-49151). These ports are assigned by IANA to specific services through a formal application process2. Anyone can request a port for their protocol or application, and if approved, it becomes part of the official registry.
Unlike well-known ports (0-1023), which require root privileges to bind on Unix systems, registered ports can be used by ordinary applications. This made them popular for commercial software in the 1990s—companies could get an official port number for their product, lending it an air of permanence and legitimacy.
Sometimes that permanence outlasts the product itself.
What Might Actually Be Using This Port
In practice, unassigned or defunct registered ports sometimes get repurposed informally. Malware has been observed using port 13763. This makes sense—an obscure, officially registered but practically unused port is perfect for malicious software trying to blend in.
If you find port 1376 open on your network and you're not running IBM Person to Person Software (you're not—no one is), investigate it.
How to Check What's Listening
On Linux or macOS:
On Windows:
If something's listening and you don't recognize it, find out what it is. Dormant port assignments are favorite hiding spots for things that shouldn't be there.
The Honest Truth
Port 1376 is a digital artifact. A line in a registry. A memory of software that mattered enough to someone, once, to request an official port assignment.
The Internet is full of these gravestones. Protocols that solved problems we no longer have. Software that ran on operating systems that no longer exist. Port numbers reserved for products discontinued before most current developers were born.
The assignments remain because there's no compelling reason to remove them, and because the port number space is large enough to hold our history along with our present.
Port 1376 isn't really a port anymore. It's a monument.
Frequently Asked Questions
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