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

Vladislav Grishenko themiron at mail.ru
Sun Aug 4 22:22:13 BST 2013


Hi Jonathan,

There's quick fix for your issue, if client hasn't specified preferred
address lifetime, lease time is used. Valid timeout value is still ignored.

 
<http://wl500g.googlecode.com/svn/trunk/dnsmasq/110-no-lifetime-preference.p
atch>
http://wl500g.googlecode.com/svn/trunk/dnsmasq/110-no-lifetime-preference.pa
tch

 

Best Regards, Vladislav Grishenko

 

From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk
[mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk] On Behalf Of
Jonathan Fabian
Sent: Thursday, August 01, 2013 4:06 AM
To: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: [Dnsmasq-discuss] DHCPv6 Server not respecting lease time setting

 

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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