[Dnsmasq-discuss] Openwrt and reboots again...
simon at thekelleys.org.uk
Wed Feb 1 19:52:39 GMT 2006
Stephen Rose wrote:
> 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
Feedback from the DHCP gurus was positive, so I've built a test version
which should behave better under these circumstances (as long as
"dhcp-authoritative" is set in /etc/dnsmasq.conf)
I'll send you a copy by private mail, please could you test it?
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