Port 620 belongs to the well-known ports range (0-1023), the section of the port number space reserved by IANA for system services that typically require administrative privileges. But unlike ports 80, 443, or 22, which carry the weight of the Internet on their shoulders, port 620 serves a narrower purpose—and has led an interesting double life.
What Runs Here
Port 620 was officially assigned to SCO WebServer Manager (sco-websrvrmgr), a management interface for SCO's web server products.1 This was part of SCO's broader suite of administration tools during the Unix wars of the 1990s, when companies like SCO (The Santa Cruz Operation) competed to provide enterprise Unix solutions.
The service runs on both TCP and UDP, though in practice, management interfaces like this typically use TCP for reliable command-and-control communication.
The SCO Story
SCO registered port 620 for their WebServer Manager, while port 598 was used for an earlier version (SCO Web Server Manager 3).2 This was during an era when Unix vendors maintained their own ecosystems of proprietary management tools—before the web consolidated around Apache and nginx, before Linux became dominant, before "the cloud" meant anything at all.
SCO OpenServer was a commercial Unix operating system, and the WebServer Manager was part of the administrative toolkit that system administrators used to configure and monitor web services. The tool is largely obsolete now. SCO itself went through bankruptcy, litigation, and eventually faded into obscurity. The ports it registered remain in the IANA database, artifacts of a different technological era.
The Unexpected Tenant
Here's where it gets interesting: port 620 also appears in gaming databases as the port used by Dark and Light, a fantasy MMORPG released in 2006.34 The game was developed by NPCube and published by Farlan Entertainment. It was not successful—servers went offline in 2008 after largely negative reviews and a lawsuit.5
The game never officially registered port 620. It simply used it. This is the nature of unofficial port assignments: developers pick a number that seems available, players configure their firewalls accordingly, and the port becomes associated with that service in practical terms, even if IANA has no record of it.
The fact that an enterprise Unix management tool and a doomed fantasy MMORPG ended up sharing the same port number tells you something about the chaos of the port number space. Official assignments don't prevent unofficial use. And once a service disappears, its port becomes available again—not formally, but practically.
Why This Port Matters
Port 620 is not carrying critical Internet infrastructure. You will not find it open on most systems. But it represents something important: the messiness of the port system, the layers of history encoded in these numbers, and the difference between official assignment and actual use.
The well-known ports range was supposed to be orderly. IANA assigns, vendors implement, everyone knows what to expect. But in reality, ports get reused, services die, unofficial assignments proliferate, and what's "well-known" becomes a matter of context.
If you find port 620 open on a system today, it's unlikely to be SCO WebServer Manager (unless you're maintaining a very old Unix box). It's unlikely to be Dark and Light (the servers have been dark for nearly two decades). It's probably something else entirely—a custom service, a development server, or nothing at all.
Checking What's Listening
If you need to see what's actually using port 620 on your system:
On Linux or macOS:
On Windows:
If nothing returns, the port is closed. If something does, you'll see the process ID and can investigate further.
The Broader Picture
Unassigned and obsolete ports like 620 matter because they show how the Internet actually works versus how it's supposed to work. The IANA registry is the map. Reality is the territory. They don't always match.
Every port in the well-known range has a story. Some carry the weight of civilization (HTTPS on 443, DNS on 53). Others carried something once and now carry nothing. Port 620 is the latter—a monument to SCO's ambitions, a footnote in gaming history, and now mostly empty space in the port number system.
But it's still there. Still registered. Still waiting for the next service that decides to use it, officially or otherwise.
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