Even though I have written about this before, with malware and virus attacks, along with the data breaches in the past several months, I recommend you make certain your firewall is turned on to help protect your Mac.
Open System Preferences from the Apple menu and then select “Security & Privacy.”
Next, select the “Firewall” tab at the top of the box. If your firewall is turned on, you will see the green dot indicating it is enabled. If it is not turned on, click the lock in the lower-left corner and then enter your password. You should now be able to select the “Turn On Firewall” button.
Next, select the “Firewall Options” button. You will need to click the lock in the lower-left corner and then enter your password if you haven’t already done so. When the box opens, look at the space just under “Block all incoming connections” and see what is listed there. Anything in this area has been given exclusive rights to allow incoming connections. If you don’t recognize any items in the list, you should remove the listing by highlighting it and then select the “-“ sign below. As a matter of fact, as I write this article, I found a listing in mine that I am unfamiliar with and I know I didn’t allow it to begin with. I actually remove all listings in this box and if it is something that is really needed, it will prompt me to allow it later.
Once you have removed the listings, put a checkmark in the box below to automatically allow built-in software to receive incoming connections. Once you are done, select “OK” and then click the lock to preserve your changes.
I recommend you look at this often because I have found on two occasions that this was changed on my MacBook Pro without my knowledge and the same thing may happen to you too.
For more than 15 years, Scott Lindsay has helped thousands of people better their skills, publishing more than 500 articles about Apple and Microsoft software, the computer and the Internet. You can reach Scott for comments or questions at ScottLindsay@live.com.