[Babel-users] newbie questions

[Gabriel Kerneis]

On Wed, Jun 29, 2011 at 05:12:36PM -0400, Kirk Reiser wrote:
> If I am running ahcp do all visiters to my network need to be running
> ahcp or do I still need to run a dhcp server to support machines not
> running ahcp and babel? 

Well, if all visitors run ahcp, they'll get an address automatically (and
help propagate ahcp messages); if they run babeld, they'll get routes
automatically (and help propagate babel message and route packets); if they
run both, everything is perfect and dhcp is not needed.

On the other hand, they might run neither, with the following caveats:
- you need to have a dedicated wireless card working in Acces-Point mode,
  since it is much easier to configure for you and your client (you control
  the routing part, they have feedback about the AP they chose to connect
  to).  You could also use multiple SSID on a single card, but it is more
  tricky to setup and less efficient.
- if your clients do not run ahcp, you need to add a dhcp and radvd server
  on every router they might connect to: contrary to ahcpd, dhcp and radvd
  have no forwarder mode, so you must duplicate the servers.  This means in
  particular spliting your dhcp allocation range to avoid leasing the same
  address several times (you have no such problem for radvd of course).
- if your clients do not run babel, you need to add static routing
  information on your routers.  Very similar to how you would configure an
  Internet gateway, except you do not need to NAT (only forward), and this
  is in fact a "Babelnet" gateway.

The ahcp/dhcp part should be made easier once Juliusz implements prefix
delegation, but I believe the work is not quite finished yet.

By the way, do not forget to disable the bridge between wifi and lan on
your routers if you want to use babel, it will be much more efficient (you
only need to add a routing rule or two to achive the same result).
 
> Also, if I am running ahcp in server mode do I still run radvd on the
> interfaces I'm using ahcp on? 

It is not necessary (but it should do no harm either).

> Oh, and what do I do with my current interfaces file entry for ifup on
> the machines running ahcp in client mode.

Hmm, what kind of machines are you talking about: OpenWrt routers or
desktop computers?
- OpenWrt routers: I advise you to chose IP addresses statically, and setup
  ahcp in forwarder mode (rather than client mode).  This is much easier to
  administrate your network.
- Desktop (or laptop) computers: disable network-manager and every
  automatic script.  Then, tweak the following script to suit your needs:
  http://www.pps.jussieu.fr/~jch/software/files/wifi-autoconf.sh

> I apologize if these are to simple but I really don't want to break the
> openness of my ad-hoc network for random visiters.

How does it work with olsr?

Best,
-- 
Gabriel