[Dnsmasq-discuss] Fast add/remove of route for dnsmasq DHCP clients

[Olszowi Bernd]

>> Hi,
>> 
>> I use dnsmasq as DHCP server for a WLAN hotspot and also got a dial
>> up network (3G/LTE) for internet connection. The internet connection
>> is not always available. Therefore I add the DHCP route option when
>> there is an internet connection and remove the route when there is
>> none. My problem is that when WLAN clients connect, when there is no
>> internet connection, they don't get the route. But when the internet
>> connection is available I have to wait for lease renewal until the
>> route is available at the WLAN device. Is there a solution that the
>> clients immediately get the new route and can start to access the
>> internet?
>
>Hi Bernd,
>what about setting the machine dnsmasq runs on as default route for the
>WLAN clients,  Then configure it to forward packets to the machine with
>the WWAN interface and also, set that machine as default route.
>So you'd get: 
>
>WLAN client -default route-> dnsmasq machine -default route-> WWAN
>gateway (which will then have it's defaultroute set by the provider).
>(IIRC, in this case, you wouldn't even have to set the default route for
>dnsmasq's dhcp).
>
>That way the WLAN clients don't have to cope with a changing default
>route, the only thing that happens if the WWAN is unavailable is that
>they're unable to reach the Internet.
>
>Hartmut
>
>
>> Same problem when internet connection shuts down. At the
>> moment I set a very short lease time (4 min) but this cause problems
>> with old Android smartphones and I have to wait ~2 min.
>> Deauthenticating all WLAN clients so that they have to reauthenticate
>> and redo DHCP is unfortunately not an option.
>> 
>> Thank you
>> Bernd

Oh sorry, I forgot.
That's also not an option because when smartphones get a route they shut down their own 3G/LTE connection and use the WLAN connection for internet access, which is not working.
If you set no route the smartphone use it's own 3G/LTE connection for internet access.

Cheers
Bernd
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