Add enftun to xap-rw-001 board config

[drbild]

Now that enftun is available as a buildroot package, we need to add it to the image for the router card with WiFi (xap-rw-001).

The router card will have two instances of the enftun, enf0 and enf1, each managed as systemd services.

enf0 is connected to an ENF subnet managed by the customer. All traffic from the host device must be routed through this interface.

enf1 is connected to an ENF subnet managed by Xaptum. It is used for management of the router card itself. All local traffic on the router card, e.g.,the mender.io software update utility, must be routed through this interface.

Main tasks

• [x] add the enftun package to the board config, also adding any missing dependencies and or kernel config changes
• [x] Create the config files enf0.conf and enf1.conf
• [x] add enftun config files and the server ca cert to the root overlay:

  /etc/enftun/enf0.conf
  /etc/enftun/enf1.conf
  /etc/enftun/enf.cacert.pem
  /etc/enftun/enf0/   # directory to hold the cert and private key
  /etc/enftun/enf1/   # directory to hold the cert and private key

• [x] Enable systemd services enftun-setup@enf0, enftun-setup@enf1, enftun@enf0, and enftun@enf1.

The enftun-setup script provided by enftun was designed to configure routing for IoT gateways and servers running enftun themselves, not the router card. It can either be extends to support the router card, or the card should use its own custom version.

[drbild]

Closed by #7