You mean like this? [1] http://rmind.github.io/npf/intro.html http://rmind.github.io/npf/intro.html [2] https://man.netbsd.org/npf.7 https://man.netbsd.org/np

You mean like this? [1] http://rmind.github.io/npf/intro.html http://rmind.github.io/npf/intro.html [2] https://man.netbsd.org/npf.7 https://man.netbsd.org/npf.7 Or conveniently integrated into Linux like in [3] https://therouter.net/ https://therouter.net/ and [4] https://github.com/alexk99/the_router https://github.com/alexk99/the_router ?