DavidR
123
Firewalls only stealth/keep out certain things, stuff like port scans, pings, attempts to access your computer without your authority.
Anything that you initiate, is automatically let through the firewall (unless you have some ports blocked/rules set up). There are lots of ways for trojans to get into your computer and deception is the major one.
You download a useful tool and you get an unwanted payload (that’s why they are called trojans). Some sites pop-up windows with all sorts of tempting offers, click OK at your peril. Some are devious and actually fire when you click the No/Cancel button, so I tend to use the X to close the window.
In those instances it wouldn’t matter what firewall you had because to all intents abd purposes the firewall believes you initiated the download.