IPv6 tunneling Caveats for 376.48_2 and windows clients. Note for internal DNS

[mlai]

IPv6 tunneling Caveats for 376.48_1 and windows clients. Note for internal DNS

Been using IPv6 via a Hurricane Electric Tunnel with AC66/AC68/AC87 for a while. Things that I noticed, but rarely mentioned, may cause problems with new setups for unmanaged IPv6 deployments.

Note for Windows clients.....
None of the Windows clients supports getting DNS information from radvd!
In fact, Windows clients will only take the network prefix, and the router advertised gateway addresses. For SLAAC (which is, the computer auto-gen an ipv6 address based on the tunnel's IPv6 prefix and the interface's mac address), the client will have NO CONNECTION TO AN IPv6 DNS server, if one enable just the radvd. You will still have IPv6 connectivity, if there is a IPv4 DNS capable of resolving IPv6 queries, which is most DNS nowadays.

So to populate Windows clients with a IPv6 DNS Server (one with IPv6 address), you will need to enable a DHCPv6 server, configured to just dish out DNS information, or for a fully managed DHCPv6 including address leasing (like DHCPv4).

Note for ASUS routers regarding DHCPv6......
IT HARD CODES THE ROUTER'S ADDRESS AS THE ONLY IPv6 DNS SERVER!
That means, it does not matter what addresses you put in for IPv6 DNS servers on the IPv6 pages (you can put in 3), your windows clients will see the router's IPv6 address as the only IPv6 DNS server for the client's IPv6 interface. This differs from the DHCPv4 implementation where, the clients get the DNS server manually configured in the webui, in conjunction with the router's dnsmasq address.

Normally speaking, this will not cause a major problem. But will be a problem if one wants a different DNS server for the clients (for example, a local DNS server more manageable than the dnsmasq......)

The way to solve this (as of now), is to make use of the dhcp6s.postconf script, to replace the router's address in the dns settings with user's dns server addresses.

Hopefully, this will help someone who wants to make use of a separate ipv6 DNS server (like I do with a Synology NAS) other than letting the ASUS routers take over all DNS queries for the local clients......

PS. The radvd on the router exhibits the same behavior, namely, it broadcasts the router as the only RDNSS to clients supporting retrieving DNS info from radvd broadcasts. Can be changed in the same way as the DHCPv6 using radvd.postconf scripting.

 

[jea101]

I copied dhcp6s.conf to /jffs/scripts, edited it with vi add my local servers before the router and did a reboot. One name server per “option domain-name-servers” line works for me.

option refreshtime 600;
option domain-name-servers 2001:470:xxxx:1::250;
option domain-name-servers 2001:470:xxxx:1::251;
option domain-name-servers 2001:470:xxxx:1::1;