macOS 15: Trouble with network filters and macOS Firewall
Renewed network problems in macOS 15: The integrated firewall slows down external network filters such as Little Snitch.
Firewalls are supposed to provide security. However, the one built into macOS 15 reduces it due to bugs.
(Image: Dario Lo Presti/Shutterstock.com)
Providers of third-party firewalls, i.e. network filters for macOS, warn against simultaneous use of the Apple firewall under Sequoia. A bug in Apple's NetworkExtension framework ensures that data is then forwarded unreliably to the third-party apps. This makes the use of tools such as Little Snitch a game of chance.
Firewall plus firewall equals bug
The creators of the app, Objective Development from Vienna, are currently also warning about the problem. According to them, the bug is still present in macOS 15.1, which was supposed to have cleaned up network-related errors reported by various security companies. While difficulties in connection with DNS queries no longer occur –, including UDP packets being discarded, which led to name server errors when using the app firewall –, the firewall issue is apparently new or is at least only now being more widely recognized.
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"As a result of this new bug, Little Snitch may not receive information about network traffic from Apple's framework, so that no traffic is displayed in the network monitor, no connection warnings are displayed and firewall rules for blocking connections are not applied," says Objective Development. As this only occurs sporadically, users no longer have any overview of what is happening on their system.
Network activities no longer arrive
The manufacturer therefore warns against running both Apple's integrated firewall (via the network settings) and Little Snitch at the same time. As the Apple firewall is often active by default, it must be turned off. In addition to Little Snitch, Little Snitch Mini is also affected. "The problem only occurs relatively rarely, so it is not reliably reproducible," Little Snitch developer Norbert Heger told Mac & i. "But when it does occur, it is in such a way that Little Snitch or Little Snitch Mini no longer show any network activity."
As soon as the macOS firewall is switched off, the data comes back immediately, "when you switch it back on, [there is] immediate silence again". Apple has not yet commented on the issue. Sometimes restarting the Mac seems to help, but then the error occurs again later.
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