I have set it up in a way where all the packets have to go through their VPN and if they don’t, they get dropped before they leave my PC.
That is the function of a firewall and not of the VPN. As I understand portmaster it does both. But that is not normal VPN behavior.
VPNs are not magic. They are a piece of software that encrypt traffic and send it to a special server. They do that by creating a virtual Internet connection (think like pluging in an additional Ethernet cable or connection to an addition WiFi at the same time). Everything that is sent through the virtual connection is encrypted. Your system now has (at least) two valid Internet connections (one real and one virtual). For every packet it sends it needs to decide which connection it should send it from. This is decided by something called the routing table. When you start the VPN it will put two routes into the table.
- traffic going to the VPN server goes through the real connection (so the encrypted VPN traffic is routed correctly)
- everything else goes through the virtual connection (the VPN tunnel where it gets encrypted)
The attack described is a way how a network router can add a new route into your devices routing table to basically override the second route from the VPN. The route is still there, there just is another one that has a higher priority.
A VPN is not the ultimate authority over your network traffic. It is just another program sending and recieving taffic.
No. It’s not a magic invisibility field inside. It’s a magic object that works only on living “intelligent” creatures. It also doesn’t work the same on different races. Only humans (hobbits are a subtype of human in Tolkiens lore) turn invisible. And because it’s magic it also turns their clothing etc invisible. So either Frodo and his poop is invisible or nothing is.