[WireGuard] doing crazy ipv6 stuff

Dave Taht dave.taht at gmail.com
Sat Sep 3 18:19:31 CEST 2016

I built wireguard on the rasberry pi 2. Aside from complaining about
padata not being enabled, it worked. I did a bunch of benchmarks and
despite dealing with some queuing issues (as described in an earlier
thread and in some email with jason, and maybe one day a blog entry)
everything worked as advertised. yay!

(there are a ton of "kernel-header" .debs for raspbian, the right one
is "raspberrypi-kernel-headers")

Two notes: on that kernel release (4.4.13-v7)

an ipv6 link local address was not created on the wg device. (on my
x86 (4.7) one is). Not sure if that matters. Then I got crazy - said
to myself, hmm, can I make babel work over this? (babel relies on ipv6
link local multicast).

On the 4.4 rpi box, even after manually putting in a fe80::whatever/64
address, putting babeld -D wg0 on it ended up with no packets showing
up in the tcpdump -i wg0.

I fiddled with crazy stuff, like adding support for transport of the
fe80 and ff02::1:6 multicast addresses...

peer: aD5ecbdSHoSPQUyr8p1KYjoS8JWADcFVF6n4dwtsfkQ=
  allowed ips:, ff02::1:6/128, fe80::/64, fd78::/64

on the x86 box, I do see babel succeeding in dumping packets in there.
(I don't have another x86 box to test with at the moment).

I really don't know if this stuff should work or not. My gut says even
attempting limited multicast capability over a vpn ends up in a world
of hurt....

a thought in terms of endpoint mobility - being able to migrate
between ipv4 and ipv6 and back would be kind of nice in some ways.

( https://arxiv.org/pdf/1502.02402.pdf )

and: I can go bug the pi folk to enable padata.

I am not in a position to provide benchmarks of the pi2 today, it's on
the other end of a very slow wifi link, and I was using wireguard for
a weird purpose - by turning on and off vpn encapsulation I could
easily test the "codel" portion of the new fq_codel for wifi code.
(and the new ecn support in wireguard worked!)

I can say it pushed 20Mbits, no problem.
Dave Täht
Let's go make home routers and wifi faster! With better software!

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