bridge

In this tutorial we are going to do a refresh on Linux network namespaces. We will start with two namespaces that can’t even ping themselves, connect them with a virtual cable, replace that cable with a bridge, give the host a leg on that bridge, and then work our way outward — routing, forwarding, NAT, route specificity, and finally port forwarding back in. Everything is done by hand with ip and iptables, so that nothing is hidden behind tooling.

To simulate an environment we will use a Linux machine via Lima and the limactl CLI. Namespaces don’t need a complicated topology — one VM is enough, because the whole point is that we’re going to build a little network inside it.