Port 1130 lives in the strange middle ground of the port number system—officially registered, technically assigned, but practically unknown.
What Port 1130 Is (Officially)
According to IANA records, port 1130 is registered to CASP (CAC App Service Protocol)1. Port 1131 is registered for the encrypted version, CASP-SSL. Both TCP and UDP are supported.
That's what the official registry says.
What Port 1130 Is (In Reality)
If you search for information about CASP or the CAC App Service Protocol, you'll find almost nothing. No RFC. No widespread implementation. No documentation about what problem it was meant to solve or who created it.
This port exists in that curious category: registered but forgotten. Someone filed the paperwork with IANA years ago, claimed port 1130 for their protocol, and then... the protocol never took off. Or it did, briefly, in some specific vertical market that left no trace on the public Internet.
The registry shows an assignment. The real world shows silence.
The Registered Port Range
Port 1130 falls in the registered port range (1024-49151)2. This range was created for applications and services that wanted an official port number but didn't qualify for the well-known range (0-1023).
Anyone can request a port number in this range by filing an application with IANA. The bar is lower than well-known ports. You don't need to prove widespread adoption or write an RFC. You just need to want one.
The result: the registered range is full of ports like 1130. Officially assigned. Practically dormant.
What Might Actually Be Using Port 1130
Just because CASP isn't widely known doesn't mean port 1130 is always quiet. Unassigned or obscure ports often get used for:
- Custom applications that need a port number and picked one at random
- Malware looking for non-standard ports to avoid detection
- Internal services that someone configured years ago and no one remembers why
- Ephemeral connections that your operating system assigned temporarily
If you see traffic on port 1130, it's probably not CASP. It's probably something else that decided to live there.
How to Check What's Using Port 1130
On Linux or macOS:
On Windows:
If something is listening on port 1130, these commands will tell you what process owns it.
Why Obscure Ports Matter
Ports like 1130 teach us something about how the Internet actually works versus how we imagine it works.
We imagine a clean system where every port has a purpose, every protocol has documentation, every number means something specific. The reality is messier. The port registry is full of ghosts—registrations from projects that failed, protocols that never launched, services that died quietly.
The well-known ports (0-1023) are tightly controlled and heavily used. The registered ports (1024-49151) are a mix of success stories and abandoned dreams. And the dynamic ports (49152-65535) are pure chaos—assigned by your OS for whatever needs them right now.
Port 1130 sits in the middle range, registered to a protocol almost no one has heard of. It reminds us that the Internet isn't a perfect system designed from the top down. It's a messy, organic thing that grew through trial and error, with plenty of dead ends along the way.
Security Note
If you find unexpected traffic on port 1130, investigate it. Obscure registered ports are sometimes used by malware precisely because no one expects to see traffic there. An empty port makes a good hiding place.
Check your firewall rules. If you're not running CASP (and you're almost certainly not), there's no reason port 1130 needs to be open.
Frequently Asked Questions About Port 1130
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