Earlier quoted context omitted.
You can run openwrt on your pi and do it that way. Once you get familiar with openwrt, it does a lot of interesting things. I did it as an experiment and have a pi running openwrt as an ntp server. it's behaved very well.
> Once you get familiar with openwrt, it does a lot of interesting things. what's your favorite feature?
one really nice feature - especially for the pi - is that the filesystem is read-only and runs with an overlay filesystem from ram. This give you the ability to see what is changed or back up your changes by accessing the overlay directly.
Another feature is the GUI. You can easily get started, but as you become familiar with the system, you can just edit the configuration files to change things.