[Dnsmasq-discuss] Openwrt and reboots again...
s9999 at penguinmail.com
Wed Feb 1 13:27:15 GMT 2006
Simon Kelley wrote:
> I'm guessing that what happens is that the client sends a DHCPREQUEST to
> renew its lease and dnsmasq returns DHCPNAK: lease not found. The client
> then does DHCPDISCOVER-DHCPOFFER-DHCPREQUEST-DHCPACK and gets a new
> lease, but for the same address. (Checking the logs on the openWRT box
> will tell you if this is the case.
> My first reaction to this is that returning a DHCPNAK to an attempt to
> renew an unknown lease is the correct thing to do, and can't be changed,
> but when I actually looked at the RFC it wasn't clear that that's true.
> In fact, RFC2131 says almost nothing about sending a DHCPNAK to a client
> in RENEWING state. (It has plenty to say about SELECTING and
> INIT_REBOOT, but that's not relevant here.)
> As far as I can see, there are no bad consequences to just accepting a
> renewal of a previously-unknown lease, except in the case that the
> renewal is broadcast (ie rebinding) and picked up by both the correct
> server and another which happens to be on the same network. To avoid
> that, I would probably only change the behaviour when the
> dhcp-authoritative configuration is set, since that already has the
> meaning of "optimise for the case that I'm the only DHCP server on this
> I'll post a query about this to IETF mailing list.
I checked the logs. That is indeed what's happening during the dialog
with Windows XP. I have a D-link access point that seems to need a
couple of DHCPREQUEST-DHCPNAK cycles before it finally decides to
DHCPDISCOVER. That device has an entry in both the ethers file and the
hosts file, so it can't get another address. At the very least, I would
expect devices that are pinned like that to not need leases. Just a
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