Challenges Detecting Active Interfaces and IPv4 Changes on macOS with SystemConfiguration Framework

I am encountering an issue while using the SystemConfiguration framework to detect IPv4 address changes and active interfaces on macOS. Specifically, I'm facing difficulties when the interface switches from one network to another.

When connected to a network with a Captive Portal enabled, I'm unable to retrieve the active interface using the stored key State:/Network/Global/IPv4. The output I receive is:

No such key

However, when I attempt to retrieve interface information using scutil --nwi, the output is as follows:

IPv4 network interface information

No IPv4 states found

   REACH : flags 0x00000000 (Not Reachable)

IPv6 network interface information
   No IPv6 states found


   REACH : flags 0x00000000 (Not Reachable)

Network interfaces: en0

Despite this output, the interface en0 is active and has a valid IPv4 address: when checking through ifconfig:

en0:flags=8b63<UP,BROADCAST,SMART,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
    options=6460<TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM>
	ether bc:d0:74:07:2a:33
	inet6 fe80::412:ec:40df:4211%en0 prefixlen 64 secured scopeid 0x12 
	inet 10.42.0.5 netmask 0xffffff00 broadcast 10.42.0.255
	nd6 options=201<PERFORMNUD,DAD>
	media: autoselect
	status: active

It's evident that the interface is active and has a valid IPv4 address, but the retrieval methods using SystemConfiguration framework are not providing the expected output. I'm seeking assistance in resolving this discrepancy and accurately detecting active interfaces on macOS. Any insights or suggestions would be greatly appreciated. Thank you.

accurately detecting active interfaces on macOS.

What do you expect to do with that information once you have it?


The State:/Network/Global/IPv4 property is missing because:

  • It reflects the default route.

  • While the network is captive, it can’t become the default route.

I explain a lot of the backstory to this in the posts linked to by Extra-ordinary Networking. Have a read through those for context.

A key takeaway from that explanation is that the best path forward depends on your final goal. Hence my question above.

Share and Enjoy

Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Challenges Detecting Active Interfaces and IPv4 Changes on macOS with SystemConfiguration Framework
 
 
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