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Topic: RFC2136 DDNS is not working over ipv6 (using 6to4 tunnel)  (Read 3832 times)
« on: November 13, 2010, 22:03:14 »
trefzer *
Posts: 1

Hi there

I probably found the following bug. I also include the workaround, and my interpretation of the problem.

Setup Domain Server:
DNS Server Bind, with dynamic domain configured. The dynamic Domain has 3 DNS which are all reachable by ipv4 and ipv6.

Setup m0n0wall:
WAN interface configured with DHCP (either directly connected to cablemodem or (second setup, different place) connected to adsl modem doing PPoE and DHCP.
Additonaly there is 6to4 tunnel configured. IPv6 is working (ping, traceroute from webfrontend and/or from LAN side)

Hardware: PCengine wrap
Firmware: m0n0wall 1.32

What works:
If I save the RFC 2136 dyndns settings a correct update of the DNS server takes place. Analyzing the logfile on the server, I realize, that the update is done via IPv6.

What does not work:
Reboot (includes IP change)  of m0n0wall and/or change of IP adress is not send to the server. So the new IP is not mentioned to DNS (failure of nsupdate).
I did not find any log entries of failures (not on m0n0wall, and not on the DNS Server).

Workaround:
To force nsupdate via ipv4 I made an aditional A record to the IPv4 adress of the primary Nameserver.
The A record is then published as additional Nameserver of the dyn subdomain. The new IPv4 Nameserver is mentioned in the SOA record as master DNS (instead of an ipv6 capable nam
eserver).

If I save the RFC 2136 dyndns settings the update of the DNS Server takes place by using ipv4.
And surprisingly updates of IP adresses on the WAN interface (after reboot, or with new leases) are now working.

Interpretation:
The initialisation of the IPv6 over 6to4 tunnel needs some time after the change of ipv4 address (6to4 ipv6 address is sticked to ipv4 address).
The nsupdate on m0n0wall is executed before ipv6 is ready. The update package sent by m0n0wall is not reaching the DNS Server.
(to switch the RFC 2136 update to tcp does actually not help !).

Well I just like to thank you the developpers for their perfect work. I enjoy using m0n0wall. Thank you.

If you have additional questions according to the bug report or need a ipv6 ddns for testing, just let me know.

Cheers

Benedikt

 
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