On Tue, Apr 18, 2023 at 08:24:17PM +0100, Simon Kelley wrote: > On 18/04/2023 16:35, 0zl wrote: > > Hello, > > > > This is an issue I've experienced > > with ESP8266 and proxy ARP on my WiFi network.
Please confirm that it is proxy ARP as in https://en.wikipedia.org/wiki/Proxy_ARP > > I was able to work around it by assigning the devices an > > infinite lease, however I think dnsmasq's behavior is undesirable. > > > > In short, ESP8266 is on a network with proxy ARP setup; getting the > > initial lease works fine, however once proxy ARP kicks in it fails to > > renew. This is the chain of events leading up to the issue: > > > > * MCU tries to renew the address > > * dnsmasq properly renews its address > > * MCU sends an ARP request to check if the address is in use and > > receives an ARP reply from the router because of proxy ARP > > * MCU mistakenly believes that the address was assigned already even > > though it was not, sends a DENIED message back to dnsmasq and tries > > again > > * dnsmasq then allocates the exact same address that the MCU just rejected > > > > I think in this scenario, dnsmasq should try to allocate a different > > address because MCU has rejected it already. > > > > Not sure what people in this mailing list think, but it feels like > > dnsmasq shouldn't be doing this. > > This situation was considered and there should be sensible behaviour. > > Dnsmasq uses a hash of the MAC address to determine which the address to > offer to the client, which would cause the same address always to be offered > to the client. But if a client returns a DHCPDECLINE reply then a global > variable is incremented. That variable is also used as an input to the hash > function, so when the client asks again for an address it should get offered > a different one. > > So, this situation has been considered, but something is going wrong in your > setup. Please could you post more details of the configuration you are using > and logs of what happens so we can try and work out what is going wrong? Yes, interesting problem. I do hope there will be libpcap files. Groeten Geert Stappers -- Silence is hard to parse _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
