Port 833 sits in the well-known ports range (0-1023), reserved for essential Internet services. But nothing essential runs here anymore. This port was assigned twice—to two different protocols—and both are now defunct.
What This Port Was Supposed To Be
NETCONF over SOAP over BEEP (2006-2024)
In December 2006, IANA assigned port 833 for NETCONF over SOAP over BEEP—a network configuration protocol that was meant to help manage routers and switches remotely.1
The problem: nobody used it. NETCONF over SSH (on port 830) became the standard instead. The SOAP and BEEP transport methods never gained traction in production networks.2
In 2024, RFC 9900 officially released port 833 back to IANA. The assignment was removed from the registry. The RFC that defined it (RFC 4743) was marked "Historic"—standards-speak for "this didn't work out."3
Mac OS X NetInfo (Before 2007)
Before the SOAP assignment, port 833 was used by NetInfo—a distributed database system in Mac OS X that stored user accounts, network configurations, and printer settings. It was part of Apple's RPC-based services that used ports in the 600-1023 range.4
But NetInfo was discontinued when Mac OS X 10.5 Leopard shipped in 2007. Apple replaced it with Open Directory, which uses different ports entirely.5
So port 833 lost its second protocol too.
What This Port Actually Is
Port 833 is currently unassigned. It's not reserved for any active service. It exists in the well-known ports range, which is supposed to contain permanent, essential assignments—but the protocols that used it are gone.
This is rare. Well-known ports are typically occupied for decades. Port 25 has been carrying email since 1982. Port 80 has been serving HTTP since 1991. But port 833 outlived both of its assigned protocols within 20 years.
Why Unassigned Ports Matter
The Internet has 65,535 ports per protocol (TCP and UDP). Most of them are unassigned. This isn't a gap—it's breathing room.
Unassigned ports serve several purposes:
Future protocols need somewhere to live. When someone designs a new network service, they need a port number. The unassigned space is where new protocols get born.
Private applications can squat temporarily. If you're running a custom service inside your network, you can pick an unassigned port and use it locally without colliding with standard services.
The namespace doesn't become cluttered. If IANA assigned every proposed protocol a permanent port number, we'd run out fast. Only protocols that prove useful in production get to keep their assignments.6
Port 833 shows the system working as intended. Two protocols tried to claim it. Both failed to gain adoption. The port was released back into the pool. Someday, something else might use it—or it might stay empty forever.
How To Check What's Using Port 833
If you want to see whether anything is actually listening on port 833 on your system:
On Linux or Mac:
On Windows:
Most likely, you'll see nothing. This port is a ghost.
The Bigger Picture
Port 833 is a historical artifact. The well-known ports range is supposed to be permanent—reserved for services so essential that every system needs to know about them. But technology moves on. Protocols die. Services get replaced.
Port 833 was assigned to NETCONF over SOAP, which never left the lab. It was used by NetInfo, which Apple killed in 2007. Now it's empty, waiting for whatever comes next—or nothing at all.
That's how the Internet works. Not every door needs to be open. Not every port needs a service. Some numbers just sit there, holding space, carrying the memory of protocols that once tried to matter.
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