Knowing what to block depends on your personal level of paranoia as well as your situation. Do you do lots of torrenting? Are you in a university that scrutinizes your network usage? Do you browse in areas of high risk for ads and malware? The
PeerBlock FAQ has some good info.
The program comes with built-in Default Lists of IP addresses to block (in the top of the image below) that you can select: Anti-P2P organizations, Malicious spyware/adware servers, Advertising/data tracker servers and Educational institutions/universities.
There are many more IP address lists you can add which you can find and research at
iblocklist. They can be used as block or allow lists depending on the list and your circumstances. But you don't want to add
too many block lists or you'll end up blocking most of the internet.
You can turn these lists on and off for web browsing by toggling the Allow/Block HTTP button in the program - the top right button in the image below:
Even when you Allow HTTP, the IP addresses in your blocklists via other transfer protocols (TCP, UDP - torrenting, etc) will remain blocked.
I also have a number of specific IP addresses in my permanent allow list for the Doki site and IRC/XDCC bots. I detailed the permanent allow procedure
here.
I hope this helps a bit - but it's worth repeating that the only
truly safe thing is not downloading copyrighted content.
