Port 192 sits in the well-known ports range (0-1023), officially assigned to a service called "osu-nms"—the OSU Network Monitoring System. The assignment is real, registered with IANA decades ago under the name Doug Karl. But the service itself? Gone. Forgotten. A ghost entry in the registry of the Internet's nervous system.
What Range This Port Belongs To
Port 192 is a well-known port, part of the 0-1023 range reserved by the Internet Assigned Numbers Authority (IANA) for system services.1 These are the ports that were supposed to be stable, permanent, assigned to protocols that would matter for years.
Most well-known ports live up to that promise. Port 80 for HTTP. Port 443 for HTTPS. Port 22 for SSH. These ports carry the Internet's lifeblood every single day.
Port 192 was supposed to be one of them. It's not.
The Assignment That Remains
According to IANA's official registry, port 192 (both TCP and UDP) is assigned to "osu-nms"—the OSU Network Monitoring System.2 The contact person listed is Doug Karl. No organization. No email. No RFC documenting the protocol. Just a name and a service designation that appears in registry files dating back to at least 1994.3
The OSU Network Monitoring System was presumably a network management tool, likely developed at or for an institution (possibly Ohio State University, given the "OSU" designation, though this connection is not definitively documented). It would have been used to monitor network health, track metrics, alert on failures—the kind of infrastructure tool that every network needed in the early days.
But somewhere between then and now, the protocol disappeared. The system stopped being deployed. The software vanished. And Doug Karl's contact information became unreachable.
What This Port Actually Carries
In practice? Nothing.
Port 192 is not used by any modern network monitoring systems. It doesn't appear in contemporary network traffic. Security scanners find it closed on virtually every system. It's an assigned port with no assignment in reality—a placeholder for a protocol that ceased to exist.
This is genuinely strange when you think about it. The IANA registry is not a museum. It's a living document that governs how the Internet communicates. Yet here sits port 192, holding space for a service that no one remembers and no one uses, preserved in the registry like a fossil in amber.
Why Unassigned (and Forgotten) Ports Matter
Ports like 192 reveal something important about the Internet's architecture: the registry is permanent, even when the protocols aren't.
When IANA assigns a well-known port, that assignment typically stays forever. Even if the service dies, even if the protocol becomes obsolete, even if the contact person disappears—the port number remains claimed. This creates a kind of archaeological record in the port registry: layers of history, some active, some abandoned, all preserved.
From a practical perspective, this means:
- The port can't be reassigned to a new service without confusion and potential conflicts
- Attackers may probe it during reconnaissance, looking for forgotten services that might still be running on legacy systems
- The space is permanently reserved even though nothing uses it
Port 192 is not alone. Scattered throughout the well-known ports range are dozens of similar entries—services that mattered once, protocols someone built with care, systems that solved real problems in their time. All gone now. All still registered.
How to Check What's Listening on This Port
Even though port 192 is essentially abandoned, you can still check if anything on your system is using it:
On Linux or macOS:
On Windows:
Using Nmap to scan a remote host:
You'll almost certainly find nothing. But in rare cases, you might discover:
- Legacy network monitoring software still running on an ancient system
- A custom application that repurposed the port for internal use
- A misconfigured service accidentally bound to port 192
If you find something listening on port 192, it's worth investigating. It's either a deliberate internal tool, or it's something that shouldn't be there.
The Human Moment
Someone named Doug Karl registered this port. Probably in the late 1980s or early 1990s, when the Internet was smaller, when getting a well-known port assignment meant your protocol mattered, when the registry was a carefully curated list of essential services.
Doug Karl built something. Named it. Registered it. The OSU Network Monitoring System ran somewhere, monitoring something, keeping a network healthy. People probably depended on it. It probably saved someone from a late-night outage. It probably had bugs, and features, and that one quirk everyone worked around.
And then, like most software, it faded. Replaced by something better. Outgrown. Forgotten.
But the registry remembers. Port 192 is still assigned to osu-nms. Still listed under Doug Karl's name. A monument to a protocol that no longer exists.
Security Considerations
Port 192 presents minimal security risk precisely because nothing uses it:
- Closed by default on essentially all modern systems
- No known exploits because there's no active service to exploit
- Low reconnaissance value for attackers
However, if you discover port 192 open on a system during a security scan, investigate immediately. An open port assigned to a defunct service suggests either:
- Legacy software still running (potential security risk)
- A custom service repurposing the port (should be documented)
- Malware attempting to hide in an obscure port (rare but possible)
Related Ports
Other well-known ports in the early registry that share port 192's character—officially assigned but rarely seen in practice:
- Port 189: Queued File Transport (QFT)
- Port 193: Spider Remote Monitoring Protocol
- Port 194: Internet Relay Chat Protocol (IRC, largely superseded)
- Port 195: DNSIX Network Level Module Audit
These ports form a constellation of Internet history—assigned, registered, and slowly fading into obsolescence while their registry entries remain.
Frequently Asked Questions
The Weight of Empty Space
Every port tells a story. Some carry HTTPS traffic securing billions of transactions. Some carry SSH connections holding together the infrastructure of the Internet. Some carry email, DNS queries, database connections—the essential functions of networked life.
Port 192 carries nothing. But its emptiness tells a story too: the story of protocols that fade, of systems that vanish, of the permanent registry preserving the temporary creations of engineers who built things that mattered in their time.
Doug Karl's OSU Network Monitoring System is gone. But port 192 remains, a ghost in the registry, holding space for a service that will never return.
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