[Babel-users] Broken connectivity using WPA ad-hoc (Was: Use of nl80211/netlink vs. ioctl)

[Baptiste Jonglez]

Hi,

On Tue, Jun 14, 2016 at 06:52:07PM +0000, Ronald Phillips wrote:
> Greetings:
> 
> I’m looking to run babel & shncpd over a WPA/WPA2 encrypted ad-hoc mesh
> via wpa_supplicant version 2.5 which has this support.  I have a
> functioning network that works fine over either an open ad-hoc mesh or
> one encrypted using WEP.  When I turned on WPA via wpa_supplicant the
> traffic between the mesh units stops.

The first step is to determine whether all network traffic is dropped when
you use WPA, or if it's just babeld being somehow confused.

First make sure that your wireless interfaces have an IPv6 link-local
address (in fe80::/8).  Then try to ping over the link-local multicast
address:

    ping6 -L -I wlan0 ff02::1

If there are some layer-2 neighbours in your ad-hoc network, you should
see some answers.  If you see nothing here, then your ad-hoc network has
broken connectivity or does not allow multicast, so there is no way babeld
can discover neighbours.  You need to figure out what went wrong in your
ad-hoc network, at layer 2.

> Looking at the net.c code it appears the babel_send & babel_recv
> routines are using the ioctl and sockets to send and receive data
> vs. nl80211 & netlink interprocess communication interface which is what
> wpa_supplicant and iw make use of.
> 
> 1.       Am I correct in my thinking that the use of ioctl & sockets vs. nl80211 & netlink is why the traffic just stops once I turn on WPA with wpa_supplicant?

I think you are mixing up two seperate concepts:

- the iovec structure, used by sendmsg() and recvmsg() to send and receive
  packets "on the wire"

- ioctl and netlink, which are used to communicate with the kernel (to get
  information about the interfaces, read/write to the routing tables, etc)

So, it is unlikely that your problem is related to ioctl/netlink.

> 2.       Any alternatives for getting a WPA encrypted mesh working other than OpenVPN or the like?
> 
> 
> 3.       Is anyone working on tranitioning Babel & Shncpd to nl80211 & netlink or should I start thinking about taking this on?
> 
> Thanks, Ron
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