[Dnsmasq-discuss] Overriding DNS server for the guest WiFi interface

[Geert Stappers]

On Thu, Dec 12, 2019 at 08:44:31AM +0100, Geert Stappers wrote:
> On 12-12-2019 04:52, Old account wrote:
> 
> > Hi,
> >
> > I have an RT-N56U (I'm using a Padavan firmware for some context)
> > router with an isolated guest wifi setup for my IOT devices. This
> > guest network is both AP clients and LAN isolated, which I confirmed
> > to be true. I have the DNS set to pihole 192.168.1.100 for my entire
> > network, but I'd like any clients that are connected to the guest wifi
> > to use 8.8.8.8 since it's not possible for any of the guest clients to
> > communicate with the pihole.
> >
> > I've been able to do this by manually tagging all of my iot devices
> > one by one with:
> > dhcp-host=XX:XX:XX:XX:XX:XX,set:dnsoverride
> > dhcp-option=tag:dnsoverride,option:dns-server,8.8.8.8
> >
> > This works on any devices that I've tagged with dnsoverride, but it's
> > host-dependent rather than interface dependent.
> >
> > I've confirmed that the 2.4GHz wifi interface is rai1 with ifconfig
> > and based on the firmware docs:
> > https://bitbucket.org/padavan/rt-n56u/wiki/EN/CommonTips#!what-are-the-existing-network-interfaces-transcript-naming-interfaces.
> > I've tried the following without success - it seems like it gets
> > ignored for any clients connecting to the guest network:
> > - dhcp-option=tag:rai1,option:dns-server,8.8.8.8
> > - dhcp-option=interface:rai1,option:dns-server,8.8.8.8
> > - dhcp-option=rai1,option:dns-server,8.8.8.8
> >
> > Is it not possible to set the dns server based on the interface?
> >
> Yes, it is possible.
> 
> But I have the correct syntax not at hand. The mailinglist archive has
> within the last four, maybe six, weeks a report on succesfull tag of
> interface name.

http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2019q4/013501.html