Setup native 6LoWPAN router using Raspbian and RADVD

Setup native 6LoWPAN router using Raspbian and RADVD

Objectives

In the following we assume that you already gone through initial setup of your Pi and enabled WPAN in the Linux Kernel. If unsure checkout our previous guides before proceeding here.

• install router advertisement daemon radvd
• configure (and test) Raspbian as 6LoWPAN router

Install requirements

In order to install latest version of radvd we first have to install some dependencies. Though they are likely already installed or available via the apt repositories in raspbian, these version are quite old. So we have to install newer versions manually - its pretty easy, so no worries here!

flex

Starting with Raspbian Stretch (since 2017) you can install flex using the APT package system:

sudo apt install flex

If you encounter any problems please open an issue and also try to build flex from source, see below.

flex (deprecated)

Download, build and install a recent version of flex as follows (as before, everything goes into opt). Note: The version of flex in Raspbian is 2.5.36 and is not supported by radvd - at least the latter does not compile.

sudo apt install bison

• first get latest flex release:

cd /opt/src
wget https://sourceforge.net/projects/flex/files/flex-2.6.0.tar.bz2
tar xjf flex-2.6.0.tar.bz2
cd flex-2.6.0
./configure

• if configure succeeds without errors and all dependencies are matched, build and install:

make
sudo make install

• that's it, step 1 done!

radvd

Now we can install the router advertisement daemon for IPv6. At time of writing this there were some issues with radvd using LoWPAN devices running a recent Linux. So we have to use a patched fork of the original repository for now.

• same, same but different we start by getting the source code and run initial configuration:

cd /opt/src
git clone https://github.com/linux-wpan/radvd.git -b 6lowpan
cd radvd
./autogen.sh
./configure --prefix=/usr/local --sysconfdir=/etc --mandir=/usr/share/man

• if configure succeeds without errors and all dependencies are matched, build and install:

make
sudo make install

• that's it -- step 2 done!

Configure 6LR

• create or edit the file /etc/radvd.conf with the following content

interface lowpan0
{
    AdvSendAdvert on;
    UnicastOnly on;
    AdvCurHopLimit 255;
    AdvSourceLLAddress on;

    prefix fd00:1:2:3::/64
    {
        AdvOnLink off;
        AdvAutonomous on;
        AdvRouterAddr on;
    };

    abro fd00:1:2:3:a:b:c:d
    {
        AdvVersionLow 10;
        AdvVersionHigh 2;
        AdvValidLifeTime 2;
    };
};

• replace the ULA prefix (fd00:1:2:3::/64) with your own random prefix within range fd00::/8. If your are bad at generating random IPv6 prefixes:
  • checkout this website
  • or use this shell script
• also replace the IP address in the ABRO section with the global IPv6 address (or ULA) of the lowpan interface, for multi hop wireless networks it is imperative to not use the link local address of the interface!
• Note: the openlabs and microship transceivers both generate a new, random LLADDR on every boot. To fix the address have a look at our other guide and the README.md.
• Note: set AdvOnLink off otherwise the prefix will not be used for stateless address auto configuration, see RFC 6775, section 5.4
• configure IPv6 address on Pi with prefix fd00::1:2:3 and interface EUI64 a:b:c:d, replace these values accordingly:

sudo ip addr add fd00:1:2:3:a:b:c:d/64 dev lowpan0
                 <-prefix->:<-EUI->

• finally you have to enable forwarding for IPv6 interfaces, otherwise Linux will not send Neighbor Advertisements with the router flag set. Hence, RIOT will drop the Pi from its router list and communication via non-link-local address will cease to function. TL;DR: enable forwarding on Pi, or it wont work! See RFC 4861, 7.2.4

sudo sh -c "echo 1 > /proc/sys/net/ipv6/conf/all/forwarding"

• to set this permanently, i.e., after reboot, modify /etc/sysctl.conf and set:

net.ipv6.conf.all.forwarding=1

Testing

• check your configfile syntax with

radvd -c

• if okay, start radvd in debug mode, run:

sudo radvd -d 5 -m stderr -n

Other stuff

• to manually send neighbor solicitation (NS) or router solicitation (RS) messages install ndisc6

sudo apt install ndisc6
# send RS via iface lowpan0
sudo rdisc6 lowpan0