A recent update on my Mint system caused the eth1 to end up being renamed as eth3 and therefore breaking all my firewall & forwarding rules. How does this happen? How can I enforce  the network interfaces names to remain consistent?
Renamed network interfaces
networking;networkcard;interface
Interfaces are usually named via udev. You can find the detailed rules for this in a file like:/etc/udev/rules.d/70-persistent-net.rulesIf udev finds a known interface it uses the name configured there. If udev finds a new interface it will give it a new name and add a corresponding rule there.You can change that file and give you interfaces a meaningful name.