Port 492: TICF-1 — The Protocol That Disappeared

Port 492 is assigned to TICF-1 (Transport Independent Convergence for FNA), a protocol that exists in the official IANA registry but nowhere else that matters. It has a name, a registrant, and both TCP and UDP assignments. What it doesn't have is documentation, an RFC, or anyone who remembers what it was for.

What Port 492 Carries (In Theory)

According to the IANA Service Name and Transport Protocol Port Number Registry, port 492 is assigned to:

• Protocol: TICF-1 (Transport Independent Convergence for FNA)
• Transport: Both TCP and UDP
• Registrant: Mamoru Ito, from pcnet.ks.pfu.co.jp

That's all we know for certain.¹

The Mystery of FNA

What does FNA stand for? What is "Transport Independent Convergence"? What problem was this protocol solving?

The Internet doesn't remember.

PFU Limited is a real company—a Japanese manufacturer of computers and document scanners, founded in 1960, now owned by Ricoh.² In the 1980s and 1990s, they made minicomputers and office systems. Someone there, Mamoru Ito, registered this port for a protocol called TICF-1.

But there's no RFC. No technical specification. No mailing list archives discussing it. No conference papers. The protocol was registered, assigned a port number, and then it vanished.

The Well-Known Port Range

Port 492 sits in the well-known port range (0-1023), which is reserved for services assigned by IANA. These ports require root privileges to bind on Unix-like systems. They're meant for standardized protocols that matter enough to claim a permanent place in the Internet's address space.

Being in this range means TICF-1 was registered early, probably in the 1980s or early 1990s, when port assignments were less formal and the Internet was smaller. You could email Jon Postel, explain what you were building, and get a port number assigned.³

Many of those early assignments became foundational: SMTP on port 25, HTTP on port 80, DNS on port 53. Others, like TICF-1, faded away as the technologies they served became obsolete or were never widely deployed.

Port 493: TICF-2

There's a sibling: port 493 is assigned to TICF-2, also registered by Mamoru Ito.⁴ Whatever TICF was, it needed two ports. That suggests a real protocol with multiple channels or services. But what those channels did, we don't know.

What You'll Actually Find on Port 492

In practice, port 492 is almost certainly unused. If you scan it on your local machine:

# Check what's listening on port 492
sudo lsof -i :492

# Or with netstat
sudo netstat -tlnp | grep :492

You'll likely find nothing. The port is assigned but dormant. Some security sites flag it as potentially used by old malware,⁵ but that's true of almost any unused port—attackers don't care about official assignments.

Why Forgotten Ports Matter

Port 492 is a reminder that the Internet is built on layers of history. The IANA registry is an archaeological record. Every assigned port represents a moment when someone thought they were building something important enough to claim a permanent number.

Some of those bets paid off. Most didn't.

TICF-1 might have been a brilliant protocol that solved a real problem for PFU's customers in Japan. Or it might have been an internal project that never shipped. We don't know. The registry preserves the name, but the context is gone.

That's the nature of infrastructure. Some protocols become load-bearing—remove them and the Internet breaks. Others fade away, leaving only a number and a name in a text file maintained by IANA.

Port 492 is one of the forgotten ones.