dhcpcd-discuss

I have trouble configuring my interface with Dhcpcd when using Linux
network namespaces (netns). My use case is to eventually configure a
Wireguard VPN using a namespace `physical` for enp0s25 and another
namespace `1` for applications communicating over the VPN. That's also
the recommended way to set up by the Wireguard project [0].

# Reproducing the error

I'm using dhcpcd from latest master (01e57be54c56f6fbe0566e3aff438588030581f9).

  # uname -a
  Linux maschine 5.4.65 #1-NixOS SMP Sat Sep 12 12:18:56 UTC 2020 x86_64 GNU/Linux

Also no dhcpcd process is running.

  # dhcpcd --exit

Test that dhcpcd without any namespaces runs fine for both setting the
interface via config file as well as providing the interface as an
argument.

  # cat dhcpcd.config
  allowinterfaces enp0s25

  # dhcpcd --oneshot --debug --config dhcpcd.config
  ... runs fine

  # dhcpcd --oneshot --debug enp0s25
  ... runs fine

Then I add a namespace physical and put my ethernet interface in it.

  # ip netns add physical

  # ip link set enp0s25 netns physical

Now I run dhcpcd inside the physical network namespace. Weird thing is
that configuring the interface by providing it via the command line
works fine, while…

  # ip netns exec physical dhcpcd --oneshot --debug enp0s25
  ... runs fine

…using the config file fails with "no valid interfaces found".

  # ip netns exec physical dhcpcd --oneshot --debug --config dhcpcd.config
  no such user dhcpcd
  dhcpcd-9.2.0 starting
  udev: starting
  dev: loaded udev
  DUID Redacted
  no valid interfaces found
  exiting due to oneshot
  no interfaces have a carrier
  exiting due to oneshot
  dev: unloaded udev
  dhcpcd exited


# Expected behaviour

I'd expect it to configure fine with an interface provided via
allowinterfaces in the config file. Also it would be nice to receive some
more logging for what interfaces where detected and why they were found
to be not valid.


Any idea what is the problem here?

Thanks, Justin

[0] https://www.wireguard.com/netns/#the-new-namespace-solution

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