[Dnsmasq-discuss] DHCPv6 Server not respecting lease time setting

[Jonathan Fabian]

Hi,

I'm seeing some strange behavior between my mac and dnsmasq (running on
arch linux arm) when getting assigned an IPv6 address. Specifically, I have
the DHCPv6 set to give out a 12 hour lease time: dhcp-range=a:b:c::1,
a:b:c::ff, 64, 12h, but it will only give the mac a 2 min lease time (as a
side note, I have also tried setting a dhcp host option specifically for
macs duid and it ignores those lease time values as well). The lease time
setting works fine with the windows machines on the same network.

Looking at the network packets, I see the mac solicit the dhcp server, the
dhcp server replies with an advertisement message offering an ip address
with a valid and preferred lifetime of 43200, then the mac replies with a
request for the advertised ip address with the valid and preferred
lifetimes set to 0 (which looking at rfc3315 should be treated as no
preference), dnsmasq then sends back a reply with the address but the valid
and preferred lifetimes only set to 120 (the min time allowed)!

The only difference I can see with the windows machines is that when a
windows machine sends the request message they copy the preferred and valid
lifetimes of 43200 from the advertise message.

Maybe I'm wrong, but it seems that dnsmasq should always be ignoring the 0
when sent, and only treating the valid and preferred lifetimes from the
client as a request at best. It seems, however, to be treating them in a
manner that overrides the explicitly configured setting in its config
files. Can anyone shed some light on this behavior?

Thanks,
Jonathan
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