Re: Network Manager Wifi thoughts

[Dan Williams <dcbw redhat com>]

On Fri, 2008-04-04 at 11:52 -0400, Martin Owens wrote:
> >  This would be problematic at best, how would NM know the difference?
> >  The Captive portals work by intercepting all the traffic and in theory
> >  work transparently.   I am actually setting up one using the Captive
> >  Portal on Aruba and also testing one Consentry switch right now and I
> >  couldn't think of an easy way to allow NM to reliably determine if it
> >  had authenticated to the Captive portal or not.   What about networks
> >  that require the use of a Proxy?   In those cases the yellow
> >  connection notification would be incorrect.
> 
> There are ways of doing it so it's an additive notification, just
> because a method can not be found at the moment does not mean that the
> idea it's self is problematic, there is a need to have a greater
> status of connectivity. But think about this from the users
> perspective, KISS! Having any sort of information about the state of
> the network hidden away until you open up firefox and try out a
> website isn't good.
> 
> >  I think I understand your intent but I personally (And I have no say
> >  in the matter ;-) ) feel that this is better off in a separate network
> >  troubleshooting tool and not in Network Manager.
> 
> I disagree strongly, another tool would be subject to complicating the
> user interfaces and would push the functionality away. Suggesting that
> it be another tool while logical is just missing the point and ethos
> of the network manager (to make managing networks easy).
> 
> So far we've had a number of suggestions that the devs could implement
> and test out, see if they work and what the problems are. Fear of
> foresight can be a terrible thing sometimes.

While I agree that an "am I really connected to the internet" notifier
would be a nice thing to have, there really are a number of problems
that make it pretty much impossible to do easily or nicely.  Others have
pointed most of these out:

1) Captive portals: these are _everywhere_, and there's no way to get
around them.  They intercept and redirect all traffic.  See also (2) and
(3) because captive portals intercept these and render them useless.

2) pinging google/root-dns/whatever: this doesn't work, because the
captive portal intercepts the ping and it looks like it's coming from a
legitimate host.  Plus, it's just bad etiquette, because every time a
connection comes up/down you have to send out some _internet_ traffic
that must be routed.  I'd like to direct you to [1] if you think this is
_really_ a good idea...

3) page-scraping google/yahoo/whatever: very problematic, because it
depends on the google page to be the same.  Yes, you can develop
heuristics but this gets quite complicated and you'll have frequent
updates just like antivirus products are updated frequently.  Same exact
problem.  Plus, users will want to configure the site they want checked
because not everyone lives in the US and wants google.com.  Every
different site would need a different ID

4) ARP-ing a known MAC: this _might_ work, but of course requires the
user to set up the known MAC for every connection, which regular users
shouldn't have to know about.

5) Proxies: pretty much explanatory; if your DHCP server doesn't send
them to you, you're out of luck and certainly can't do (3) even if you
wanted to, even though you may be able to access other services

A _big_ problem here, and one that you may not realize, is of user
trust.  If there are so many difficulties with determining whether or
not the user has actual internet access, how can the user really trust
the icon?  Either it won't show up when you really _do_ have access, in
which case you have to pretty much ignore it because it's wrong much of
the time, or it will show up when you _don't_ have access (ex. captive
portals), at which point you can't trust it either.  There's a real
danger that we'd got to a lot of effort to implement the feature which
would then be quite useless to users because they can't actually trust
that the icon is correct or not.

The big question I have is "What does Vista do?"  Vista has a feature
where it _does_ show a little globe over the device icon in the system
tray when it has determined that you are connected to the Internet, and
not just your local network.  That said, it's pretty flaky and drops out
quite a bit.

In the end, it's certainly possible for an external tool to do this and
provide it's own D-Bus interface telling apps whether it thinks there's
a connection or not.  It could listen to  NM and when there's a network
connection, do it's discovery and send out it's own signals as
appropriate.  If somebody wants to do that, that would be great.  I'd
like to see a working implementation with a pretty high success rate
(90%+) before I'd consider pulling this functionality into core NM.

Dan

[1] http://pages.cs.wisc.edu/~plonka/netgear-sntp/