Ad-Hoc Configuration {#ad-hoc-network-config}

You can use to specify shell commands to be run after the network interfaces have been created, but not necessarily fully configured. This is useful for doing network configuration not covered by the existing NixOS modules. For example, you can create a network namespace and a pair of virtual ethernet devices like this:

{
  networking.localCommands = ''
    ip netns add mynet
    ip link add name veth-in type veth peer name veth-out
    ip link set dev veth-out netns mynet
  '';
}

::: {.note} The commands should ideally be idempotent, so it's recommended to perform cleanups of the state you create (e.g. virtual interfaces), or at least make sure possible failures are handled. :::