Port 385 sits in the well-known ports range (0-1023), officially assigned by IANA to a service called "ibm-app"—IBM Application.1 The registration lists a contact name (Lisa Tomita) and specifies both TCP and UDP. That's where the trail ends.
What does IBM Application do? Nobody seems to know anymore.
The Mystery of ibm-app
The IANA registry contains thousands of port assignments. Most come with RFCs, documentation, protocol specifications. Port 385 has a name and nothing else. No RFC. No protocol description. No surviving documentation explaining what service IBM ran on this port or why it needed a well-known assignment.
This happens more often than you'd think. A company requests a port number in the 1980s or 1990s. IANA assigns it. The product ships, or maybe it doesn't. Decades pass. The people who knew what it was for retire. The documentation disappears. The registration remains.
Port 385 is a bureaucratic ghost—officially assigned, functionally forgotten.
Well-Known Ports Without Well-Known Services
Port 385 belongs to the well-known ports range (0-1023), a space originally reserved for standardized Internet services managed by IANA.2 Getting a well-known port assignment meant your service was important enough to deserve a permanent, globally recognized address.
But importance fades. Standards change. Products get discontinued. The port number remains in the registry forever.
Port 385 reminds us that the Internet's address space is full of archaeology—layers of forgotten decisions, abandoned protocols, and services that mattered once.
What This Port Teaches Us
Reserved doesn't mean active. Just because a port has an official assignment doesn't mean anything is actually using it. Port 385 has been reserved for IBM Application for decades. That doesn't mean IBM Application is running anywhere.
Documentation dies. Code can be reverse-engineered. Protocols can be analyzed from packet captures. But if nobody wrote down what a service was for, that knowledge can simply vanish.
The registry is permanent. IANA doesn't reclaim abandoned port assignments. Once assigned, port 385 will be "ibm-app" in the registry until someone does the archival work to document what it actually was—or admits we'll never know.
Checking What's Really There
If you see port 385 listening on your system, it's worth investigating. To check what's using it:
Linux/Mac:
Windows:
If something is listening on 385, it's probably not the original IBM Application. It might be:
- Custom software that picked an "unused" port
- Malware using an obscure assignment to hide
- An IBM product you're running that still uses legacy port assignments
The point is: verify. Don't assume an assigned port means legitimate traffic.
The Honest Truth About Unassigned Space
Most well-known ports (0-1023) have clear assignments. Port 385 is officially assigned but functionally unassigned—registered to a service that left no trace.
This makes it effectively available for unofficial use, even though it's technically claimed. You could run your own service on 385 and probably never conflict with IBM Application, because IBM Application doesn't seem to exist anymore.
But the registry still says it's taken. That's the strange bureaucracy of Internet infrastructure—assignments last forever, even when the assignees are gone.
Why This Matters
Port 385 is a reminder that the Internet is built on layers of history. Some of those layers are well-documented standards we depend on every day. Others are mysteries—registrations without explanations, names without stories, ports assigned to services that vanished.
The registry preserves the claim. It doesn't preserve the knowledge.
Somewhere, someone at IBM knew what ibm-app was. They requested port 385 for a reason. They built something that needed a well-known address. That knowledge is gone now. The port number remains.
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