Ubuntu netplan

UPDATE: Revised 2018 11 23

If you use Ubuntu or derivatives on a computer connected to your LAN/Internet and an AREDN localnode and you have moved on to version 17.04 or 18.04 or later, then you will encounter a new network configuration system called 'netplan'. I have spent 2 weeks trying to make a workable configuration file for routing to LAN, Internet and AREDN and found that this 'new' tool (it is over a year old) is poorly documented and totally non-obvious.

Disclaimer: I am not a network engineer. I am just a domestic user of Xubuntu for 10+ years.

For Ubuntu users who just 'upgraded' and ran into this latest insanity from Canonical, attached is a natplan config file that seems to work ok - it has been working for over a week now.

First do

sudo apt remove ifupdown

If ifupdown is present it seems to mess up netplan.

then check for presence of

/etc/cloud/cloud.cfg.d/

If it is present you need to disable it, see this post:

https://www.itzgeek.com/how-tos/linux/ubuntu-how-tos/netplan-how-to-configure-static-ip-address-in-ubuntu-18-04-using-netplan.html

Next, rename the attached 01-aredn-init.txt file to 01-aredn-init.yaml and place it in /etc/netplan/ directory.
The file must be root:root and 644.

*.yaml file(s) in /etc/netplan is/are the configuraion file(s) that netplan tries to use, so EITHER REMOVE ALL OTHER *.yaml files or rename them to *._yaml else netplan will try to use them all.

NOTE: The *.yaml file format is very strict on indentation! It does NOT understand tabs (!), you must use only spaces for the indentation. Two space steps work.

Modify the addresses in this file to fit your local network. See explanations below for what some lines do.

Explanations:

eth1 is the device name of a USB-Ethernet adapter, connected to my LAN on which is a DSL modem at 192.168.1.1 providing internet access.

dhcp4: false  means don't use DHCP on this connection, use the following settings instead.

addresses: [192.168.1.21/24] means 'apply IP address 192.168.1.21 to this device, and it provides access to 192.168.1.*' (the most significant 24 bits are a netmask).

gateway4: specifies the address of the (onward) gateway for traffic through this device, the DSL modem in this case.

nameservers: specifies the nameservers to use for Internet.

eth0: is the device name of the RJ45 ethernet socket  which is connected to the AREDN radio.
dhcp4: true  means get all the settings from the connected device, the AREDN radio.

Then do

sudo netplan generate

sudo netplan apply

then ifconfig and route to see if the results look sane.