Earth Notes: On Setting Up a Raspberry Pi 3 as Off-grid Server and WiFi AP

(IN DEVELOPMENT as of 2018/07: the live server is still the RPi 2.)

As of 2018/07/13 I thought that my stand-alone Technicolor TG582n router had died, though it seemed OK again after several hours powered off. But it consumes ~8W and crashes about once per month. Also, since it is talking PPPoE (PPP over Ethernet) to a BT Openreach ECI Telecom ON316150 FTTC modem it doesn't need to do anything analogue, so the routing and filtering done by the Technicolor ought to be do-able by a Pi. Also the Pi 3 has on-board WiFi that can be used as an access point.

Another advantage of an upgrade to the Pi 3 is a bit more speed, and a bigger range of power draw to make better use of available sunshine, etc. Though I have to see if the base consumption of a stripped back Pi 3 is still OK.

I can also take the opportunity to SD card boost storage, and effectively keep the old SD card as backup.

Yet another advantage of an upgrade is moving to a newer OS distribution, allowing access to a newer Apache, HTTP/2, and various other goodies.

So an RPi 3 Model B+ and mains and 12V power supplies and other goodies have been ordered from RS to get started.

I'll record below as I prototype various aspects of PPPoE networking, new HTTP/2 support, etc.

I anticipate a fair period of prototyping and testing before (re)building the production server.

Start

Starting with just the following RS parts, no keyboard or mouse or screen plugged in, and waiting for it to boot, settles to 2.5W power consumption measured at the mains.

Directly plugging in the USB keyboard and mouse from a previous Maplin Raspberry Pi kit (R45Pi) raises consumption to 3.4W. Plugging in HDMI doesn't add any further load/consumption.

Have logged in and changed the default password for user 'pi'.

The Wifi does not seem to be in use to grab an IP (with DHCP) and get an Internet connection. This may be normal for NOOBS.

Via the Preferences menu entry and the Raspberry Pi Configuration tool I have:

• Set the system to boot to CLI rather than desktop.
• Set GPU memory to minimum (16MB).
• (NOT enabled SSH yet.)
• Set WiFi country to GB.

I am being asked to reboot for some of those to take effect.

I am still being auto-logged-in, which on the console is probably OK.

ifconfig now shows wlan0, though not with an IP address.

uname -a shows ... 4.9.80-v7+ #1098 Fri Mar 9 19:11:42 GMT 2018 armv71 ...

Following Setting WiFi up via the command line I sudo raspi-config and in "Network Options" enter SSID and passphrase. I exit raspi-config and ... I have an IP address on wlan0 and can ping the outside world!

Security dictates that the very next thing to do is sudo apt-get update && sudo apt-get-dist-upgrade.

With all that finished, power consumption (measured at the mains) is 3.1W. (Unplugging the USB mouse seems to push that up to 3.2W!)

I have established that the RPi3 and WiFi are working. Also that power consumption is not outrageous even before any attempts to tune it.

PPPoE and AP

The next step may be to load up a minimal Raspbian, and (briefly) get the RPi3 talking PPPoE to my ISP and providing a WiFi Access Point. This would probably have to be a quick temporary swap-out with the current server, as none of the other services would be there, so there will be HTTP and mail server fails while the RPi is in place.

I also have to provide down-stream wired routed (and NATted) Ethernet connections for devices that need it, such as my Loop and SmartThings hubs, and my new storage system. They may need some protection against external attack, and possibly against being used to attack other things inside the house. So I'll need to adjust my iptables config.

IN PROGRESS