Allow to set different DNS server for VoIP

[FrancYescO]

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from https://github.com/Ansuel/tch-nginx-gui/issues/349

[Ghost9090]

su tutti i fritzbox questa cosa è possibile farla, magari ansuel potrebbe riuscire a farlo per il modem tim

[Ghost9090]

@Ansuel

[Ghost9090]

Ho provato a configurare il VoIP come sui fritzbox senza successo.. solo con i DNS di Tim funziona.. @FrancYescO @Ansuel

[nclmrc]

Sinceramente se usi per la wan i peer dns di tim, e nel dhcp metti i dns per la lan hai risolto secondo me.

[Ghost9090]

Già quello lo so, ma è meglio averli anche sui dns internet invece di averli solo sul dhcp

[kevdagoat]

We could do this by creating an independent interface for VoIP (eg. voip_link) and then use dnsmasq or /etc/config/network to specify the dns server.

[nutterthanos]

Why would you want a different dns for your voip?

[FrancYescO]

Cause some (italian) providers of voip use fqdn, resolvable only from their specific DNS server.

[nutterthanos]

So the default dns server for voip on those gateways are like the isp one but they need a different one?

[FrancYescO]

Temporary solution for TIM Italy (thanks @bandit400):

for i in $(cat /tmp/resolv.conf.ppp  | grep -v '^#' | grep nameserver | grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}');
do
  uci add_list dhcp.@dnsmasq[0].server="/telecomitalia.it/$i"
done   

uci commit dhcp
/etc/init.d/dnsmasq restart

[adripo]

An alternative is to append the auto discovered TIM DNS in /etc/dnsmasq.conf as follows:

server=/telecomitalia.it/85.38.28.4
server=/telecomitalia.it/85.38.28.5

85.38.28.4 and 85.38.28.5 are examples of possible TIM DNSs

After this step it is possible to disable Auto Discover DNS in Internet Access, set custom DNS, and VOIP will continue to work properly.