Odd Permission from firewall regarding Adguard


New Member
Hi there,

First off, I must say that I love your product. I’m an undergrad university student and even with my constrained college budget, I recently bought a lifetime Adguard license for my Mac. I also purchased a license for the iOS Adguard as well.

I’m a security conscious user and like to maintain control on all of my devices. Therefore, when I switched over to macOS from Windows recently, I looked for a solid firewall product to monitor my outgoing connections. I bought the Little Snitch firewall app and it has been working splendidly.

Recently, however, Little Snitch threw an odd message regarding Adguard. The message stated that Adguard via adguard-tcpkill was attempting to access: /dev/bpf0 (Berkeley Packet Filter)

Here is a direct link to an image of the alert from my firewall:
I have also attached the image to this post.

What is this Berkeley Package Filter and should I allow Adguard access to it? Currently, my firewall (Little Snitch) is restricting Adguard’s access to it - whatever it is. Adguard seems to be working fine but my browser is acting very strangely.

I use Mozilla Firefox and every time I launch this browser, my entire OS freezes for 5-8 seconds after which the browser finally appears. Then, the browser freezes up for another 2-3 seconds. After that, everything goes back to normal. Is this odd behavior related to Little Snitch blocking adguard-tcpkill from /dev/bpf0 (Berkeley Packet Filter)?

Some information:
OS: macOS Mojave (v10.14.6)
App: Adguard for Mac (v2.1.2.595 release (CL-1.4.138)

Thank you and I look forward to hearing from you soon.




Support Marine
Staff member

Hello there!
TCPKill is Used to break browser connections established before AdGuard protection is enabled to be sure that all new requests will be filtered.
Therefore, you need to allow access to AdGuard.