Port 1623 is officially registered with the Internet Assigned Numbers Authority (IANA) under the service name "jaleosnd" for both TCP and UDP protocols.1 But here's the strange part: there's almost no documentation about what jaleosnd actually does or did.
The Registered Ports Range
Port 1623 sits in the registered ports range (1024-49151). This is the middle tier of the port system:
- Well-known ports (0-1023) are reserved for common services like HTTP, SSH, and DNS
- Registered ports (1024-49151) are assigned by IANA to specific services upon request
- Dynamic/ephemeral ports (49152-65535) are available for temporary use by any application
When someone builds a network service and wants a dedicated port number, they can apply to IANA for a registered port. IANA grants the request, adds it to the official registry, and that port number becomes associated with that service forever.
In theory.
The Ghost Service
Port 1623 was registered to jaleosnd. But what is jaleosnd?
The honest answer: we don't really know. The IANA registry lists the name but provides no description, no RFC, no documentation about what the service does. Web searches turn up the port number and the name "jaleosnd" echoed across port reference sites, but no actual information about the protocol or its purpose.2
This isn't uncommon. The Internet has been around long enough that some services were registered, used briefly (or never), and then abandoned. The port number remains claimed in the registry, but the service itself has vanished. No one maintains it. No one remembers what it did. The port becomes a ghost—technically occupied, practically empty.
Why This Happens
The port registration system operates on a "first come, first served" basis. Once a port is assigned, it generally stays assigned. There's no mechanism to reclaim ports from services that stopped existing.
So the Internet's port registry accumulates history like sediment. Every abandoned project, every failed protocol, every company that went out of business—they all leave port numbers behind, officially claimed but functionally unused.
Port 1623 is one of those fossils.
What Might Be Using Port 1623
Just because the official service is gone doesn't mean the port is always empty. Any application can listen on any port (above 1023) if nothing else is using it. You might find:
- Custom enterprise applications that picked 1623 arbitrarily
- Malware (some sources note that trojans have occasionally used this port)3
- Nothing at all
Some references incorrectly claim port 1623 is used by Microsoft Remote Assistance, but that's not accurate—Remote Assistance uses port 3389.4
Checking What's on Port 1623
To see if anything is actually listening on port 1623 on your system:
On Linux or macOS:
On Windows:
If nothing returns, the port is closed. If something appears, you've found whatever decided to claim this ghost's address.
Why Unassigned Ports Matter
The existence of ports like 1623—officially registered but functionally abandoned—reveals something about how the Internet works. The port system isn't perfectly managed. It's not a clean database maintained by some all-knowing authority. It's a registry that accumulates history, including the history of things that stopped mattering.
This is fine. The 65,535 available ports are enough that we haven't run out. But it means that when you look at a port number, you can't always trust that the "official" assignment reflects reality. Port 1623 is registered to jaleosnd. But jaleosnd doesn't exist anymore, if it ever really did.
The port remains. The service is gone. That's the Internet's version of an abandoned building—still on the map, but nobody's home.
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