Hello,
I don't want to announce any DNS neither using RAs (RDNSS) nor DHCPv6 stateless, using odhcpd. However, if I don't set anything in /etc/config/dhcp it will always send the router's IPv6 address as DNS. I can also see this from Linux using rdisc6.
This is my config:
config dnsmasq
option domainneeded '1'
option boguspriv '1'
option filterwin2k '0'
option localise_queries '1'
option rebind_protection '1'
option rebind_localhost '1'
option local '/lan/'
option domain 'lan'
option expandhosts '1'
option nonegcache '0'
option authoritative '1'
option readethers '1'
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.auto'
option localservice '1'
config dhcp 'lan'
option interface 'wan'
option ignore '1'
option ra 'server'
option ra_default '1'
option ra_management '0'
option ra_dns '0'
# list dns '::1'
# list domain '::1'
config odhcpd 'odhcpd'
option maindhcp '0'
option leasefile '/tmp/hosts/odhcpd'
option leasetrigger '/usr/sbin/odhcpd-update'
I've read so far that it is not possible to set the O-bit to zero (it is always on by default, even if M-flag is set to 0; i.e. M=0, O=1). But that shouldn't be a problem since I didn't setup DHCPv6 for the interface anyways. And even though I set "option ra_dns '0'", I still see RDNSS information in the router advertisements.
Only workaround seems to be to set "list dns" to something like "::1". I really don't want any DNS to be published. Just IPv6 address and default gateway using SLAAC.