[Dnsmasq-discuss] dhcp-pd, and autoassigned internal interfaces issues

[Dave Taht]

Both dnsmasq in git head and odhcpd in openwrt do as close to the
right thing as possible now.

I released a version of cerowrt that worked "right" in this scenario
yesterday, specifically for comcast
subscribers, with the patch for dnsmasq (if you want to use that) but
with odhcpd support by default.

The latter is upstream in openwrt, and dnsmasq 2.68 (with the less
than desirable filter) is not there either,
yet, so that's all good.



On Wed, Jan 22, 2014 at 9:56 AM, John Gorkos <jgorkos at gmail.com> wrote:
> So, in this scenario, what's the appropriate configuration to allow machines
> in the network served by the delegated prefix to get SLAAC addresses and
> provide them with Route Advertisements?
> This goes back to the question that I asked in November that got no
> traction:
> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2013q4/007810.html
> , as I'm using a Comcast DHCPv6 assigned address with prefix delegation as
> well.
>
> John Gorkos
>
>
>
> On 1/22/14, 6:37 AM, Simon Kelley wrote:
>>
>> Patch applied.
>>
>>
>>
>> Cheers,
>>
>> Simon.
>>
>> On 21/01/14 16:19, Dave Taht wrote:
>>>
>>> I have finally got my first-ever comcast ipv6 set of users up, and we
>>> have a problem
>>> with the interrelationship between addresses assigned dynamically by
>>> dhcpv6-pd and other means in dnsmasq 2.68.
>>>
>>> What happens now is that dhcpv6-pd works but dnsmasq 2.68 filters out the
>>> interface
>>>
>>> 13: sw00:<BROADCAST,MULTICAST,UP,LOWER_UP>  mtu 1500 qlen 1000
>>>      inet6 2601:X:Y:9a1::1/64 scope global dynamic
>>>         valid_lft 182420sec preferred_lft 182420sec
>>>
>>> so sends no ras.
>>>
>>> adding a second "stable" interface dnsmasq picks up.
>>>
>>>
>>>      inet6 2601:3:8180:9a1::2/64 scope global
>>>         valid_lft forever preferred_lft forever
>>>
>>>
>>> this check was not in dnsmasq 2.66, and was put in later for fairly
>>> sound reasons
>>> (like you don't want to start serving RAs on a SLAAC assigned
>>> address), but in the
>>> dhcp-pd case or otherwise assigned by the router (6in4) case, we do.
>>>
>>> Anyway the below patch "fixes it" but I'd like there to be some clear
>>> indicator
>>> of where things came from somehow.
>>>
>>>> From 4f55df81d69d20230e18c90d772904372b2b90a4 Mon Sep 17 00:00:00 2001
>>>> From: Jonas Gorski<XXXXX at openwrt.org>
>>>> Date: Wed, 8 Jan 2014 11:55:08 +0100
>>>> Subject: [PATCH] allow dhcp range construction with non-permanent
>>>> addresses
>>>
>>>
>>> The linux kernel treats all addresses with a limited lifetime as being
>>> non permanent, but when taking over the prefix livetimes from upstream
>>> assigned prefixes through DHCP, addresses will always have a limited
>>> lifetime.
>>>
>>> Still reject temporary addresses, as they indicate autoconfigured
>>> interfaces.
>>>
>>> Contributed by T-Labs, Deutsche Telekom Innovation Laboratories
>>>
>>> Signed-off-by: Jonas Gorski<jogo at openwrt.org>
>>> ---
>>>   src/netlink.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/src/netlink.c b/src/netlink.c
>>> index 3be94ee..d5de4ab 100644
>>> --- a/src/netlink.c
>>> +++ b/src/netlink.c
>>> @@ -265,7 +265,7 @@ int iface_enumerate(int family, void *parm, int
>>> (*callback)())
>>>       if (ifa->ifa_flags&  IFA_F_DEPRECATED)
>>>         flags |= IFACE_DEPRECATED;
>>>
>>> -    if (ifa->ifa_flags&  IFA_F_PERMANENT)
>>> +    if (!(ifa->ifa_flags&  IFA_F_TEMPORARY))
>>>         flags |= IFACE_PERMANENT;
>>>
>>>       if (addrp&&  callback_ok)
>>>
>>>
>>
>>
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>> Dnsmasq-discuss at lists.thekelleys.org.uk
>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>
>
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-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html