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.
Okay, from the top:
A firewall is a program or a piece of hardware that stops programs or computers on the Internet from connecting to your computer.
Your ISP guy is correct. Every modern router and cable modem/router combo has a built-in firewall, called a "NAT firewall." This is an extremely robust firewall that, for the most part, makes software firewalls like the one built into macOS redundant. And indeed, multiple firewalls can conflict, if you want another computer to connect to you. You must configure both firewalls to permit this.
When do you want another computer to connect to you? Any time you want someone to be able to reach you over the Internet. Why might you want that? Because you're hosting a game, because you're running a file server so that you can access your files at home when you are on the road, because you want to be able to use Find My Mac or Back To My Mac, because you want to be able to control your computer when you're on the road, and so on.
Little Snitch is not a firewall. Little Snitch stops programs on your computer from talking to the Internet.
Examples of programs on your computer that talk to the Internet include:
Your email program.
Your Web browser.
Apple Software Update.
Video games.
FTP programs.
Skype.
Messenger.
Chat software.
Any program that uses an automatic updater.
Adobe software (Photoshop, Lightroom, Indesign, and so on).
Basically, most modern programs talk to the Internet. Little Snitch blocks them unless you allow then to connect.
Little Snitch won't conflict with firewalls, because they do different things.
Also, your router is indeed a radio. When you connect by WiFi, your computer is talking to your router with radio waves.
