Enabling Connectivity Checking in NetworkManager

[Scott Kitterman]

On Wednesday, July 11, 2012 12:24:15 AM Jeremy Bicha wrote:
> On 10 July 2012 17:01, Marc Deslauriers <marc.deslauriers at canonical.com> 
wrote:
> > Actually, why are we running it every 5 minutes? Wouldn't it make more
> > sense to run it every 5 minutes only if we don't have a connection, and
> > only turn it on following certain events, such as a new network
> > interface coming up, or when the user logs in?
> 
> Because captive portals are not to be trusted. I believe most of them
> time out after an hour or a day or some other arbitrary length of
> time. Just because you can access the web now doesn't mean you will be
> able to 10 minutes from now.

For hotels, I can't recall the last time I had one last less then 24 hours.  
Even on public wifi (as in coffee shops), the shortest I recall one lasting was 
4 hours.  I agree that every 5 minutes is excessive.

The fundamental problem with periodics like this is that whatever $PERIOD you 
pick, the situation can change immediately after a check.  Fundamentally, I 
think that this check leaves you knowing less that it probably appears it 
does.

If Ubuntu is going to work on mobile devices, it's going to have to deal with 
intermittent apparent connectivity (it's not rare for me to have very similar 
problems when tethered via my phone - I'm connected to the phone just fine, but 
it's network connection dies for a bit).  Captive connections like hotels use 
is only one, special case of this.  Even if I didn't have reservations about 
phoning home as a concept, I don't think it solves enough of a problem to be 
worth doing.

If I've just connected to a hotel/public wifi, I know I need to go to a web 
page and sign in.  I think anyone that's ever done this before on any 
operating system knows this.  Intermittent 3G/4G connection loss produces 
similar problems, but is completely unpredictable.  I think that's a more 
important problem to solve.

Scott K