Wireless activation improvements.

[Martin Langhoff]

On Wed, Dec 10, 2008 at 11:33 PM, Michael Stone <michael at laptop.org> wrote:
> Therefore: do we have any
> interest in developing such a feature?

Yes, we want this.

The main thing with 802.11abg is that we need to pick an essid using a
reasonably stable mechanism. A few months ago we discussed the topic
of selecting an essid (on techteam - no archive link, sorry). The
summary I have of that conversation is that we can hardcode an essid
prefix or suffix and assoc to the first open signal matching it:

 - Local deployments will probably want to use an ESSID that means
"school" in a local language. (Sidenote: is utf-8 usable in ESSID
strings? Sorting/collation rules to pick "the first" matching utf-8
ESSID are a potential headache.)

 - An alternative is to just hardcode 'SCHOOLSERVER'. The same signal,
however, will be usually be used to associate to the XS, so it's
better that it has a localised name for when users pick it from the
'Network view'.

 - Mitch offered to code up a chooser UI, but it was later agreed it
was overkill.

 - The ad-hoc IPv4 self-assignment done for mesh is ugly but ok. The
XS will talk to IPv4 addresses in that range over mesh or abg.

 - This assumes the signal will be unencrypted. Supporting encryption
so early in the game adds a lot of complexity - complex WiFi setups
can broadcast an unencrypted ESSID for activation services, and an
encrypted signal for the rest of their traffic.

 - If/when we get a stable Libertas HostAP driver, we can teach the XS
to run such a dual-signal configuration if desired.

 - One thing to keep in mind: no matter what technique we use to pick
the ESSID, someone with an AP set to the same ESSID and channel can
DoS us and make a bit of a mess. There aren't any usable workarounds.
OTOH, we can tell good data from bad as is signed.

cheers,


m
-- 
 martin.langhoff at gmail.com
 martin at laptop.org -- School Server Architect
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