I have been thinking about adding Little Snitch to my extensions. When reading the reviews, it is referred to as a firewall. I don't know if Adware or any other ad- stopping extension is considered a firewall but.......way back my ISP guy (small company) said that my modem or was it my router - had a firewall built in and if I put up the firewall in my Mac they could conflict. So, I never did that.
I am wondering if Little Snitch (if it is a firewall)I would conflict with the firewall in my modem more router? He also calls the modem a radio.
