Little Snitch Blocklists

What is Little Snitch?

Little Snitch is a network monitor & application firewall for the Mac OS. On 21st May 2024, with the release of Little Snitch 6.0, a notable Blocklists feature has been made available.

While the ability to add a custom blocklist existed in prior versions, it was a manual step. Little Snitch 6.0 changes that. Little Snitch 6.0 now provides a prepopulated list of blocklists for blocking Advertising, Malware, Tracking, Gambling etc.

Little Snitch Blocklists

Little Snitch Blocklists

Considering that the StevenBlack hosts file is one of the premier list for blocking adware, I was surprised not to find the StevenBlack blocklist in the list.

The other nice addition to the list is URLhaus. At the time of writing, there were 183 malicious domain names in the list.

And, the lists auto-update,

What is the advantage of blocking using Little Snitch over a browser extension like uBlock Origin?

I use both the methods. But the method of using Little Snitch is more powerful because it covers access to network connections (adware/malware etc) from any process in the Operating System and not just from those made from within the browser.

For example, Skype making a connecting to dns.google will be detected and can be blocked using Little Snitch.

Little Snitch detecting Skype connection to dns.google

It’s also important to note that this method of blocking network communication using an application firewall like Little Snitch might not scale if the blocklist is pretty large.

For example, the newly registered domain names dataset will most definitely cause the application to misbehave. In such cases, nothing beats having protection by using a DNS Firewall/DNS RPZ (Protective DNS).

Open Snitch for GNU/Linux

On similar lines to Little Snitch, Open Snitch is a GNU/Linux application firewall. Though I have to mention that I haven’t tried it yet.

Little Snitch can also be used to capture network traffic of a specific process.

sdns://2021 – Hyperlocal root and LocalRoot

Image Source: sdns2021.dnscrypt.info

I had the opportunity to present on Hyperlocal root and the LocalRoot project at sdns://2021 last week

I’ve written and presented about Hyperlocal root aka RFC 8806 in the past. In the context of privacy, Hyperlocal root does provide a possible solution to the problem,

Prevent snooping by third parties of requests sent to DNS root servers

RFC8806

Aside from that, faster negative responses to non-existent domains eliminates junk to the root

Speaking of junk to the root, I did mention in my presentation that Chromium 87 has stopped sending junk queries to the root based on the Chromium bug report and Verisign’s blog post Chromium’s reduction of root DNS traffic

I did a quick check with Google Chrome 92.0.4515.131 and oddly enough I am still seeing this behaviour,

Aug 16 09:03:24 unbound[1:0] info: 192.168.100.4 ckgydztukkdsta. A IN
Aug 16 09:03:24 unbound[1:0] info: 192.168.100.4 lubdcupibujjne. A IN
Aug 16 09:03:24 unbound[1:0] info: 192.168.100.4 ltvlataieb. A IN

This will need further researching and debugging which I will save for another post.

A big thank you to Frank for organising sdns://2021 and also to folks from Quad9 for their help.

For some reason as can be seen in the video, presentation is stuck at a specific slide, the PDF can be found here

All the presentations are available on Youtube.