On Wed, Apr 19, 2023 at 03:16:37AM +0300, 0zl wrote: > On 4/18/23 22:51, Geert Stappers wrote: > > 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 > > Yes this is proxy ARP in https://en.wikipedia.org/wiki/Proxy_ARP.
Acknowlegde > HostAPd has an option called proxy_arp which setups up proxy_arp > with additional requirements to meet the Hotspot 2.0 standards. It > comes built in with a couple of snoopers, including a DHCP snooper to > configure proxy_arp without the need for additional software. Somehow I do read: "I could make it complicated, so I made it complicated" The good thing, the thing I might regret, is that we have now this interesting problem ... > > > > 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. > > > > I've attached a pcap file, See it. > if you need any more logs or information please let me know. Simon already did: > > > 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? > Only thing I've changed for this capture is setting the lease > time to 2m in order to make it faster for me to capture this for you, > in normal operation it was set to 8hours. Have that visible in the configuration file. > Note that the capture includes a ARP probe from the ESP Which package number (which package numbers) in the .pcap are we talking about? If it are 6 and 7, say so. > and no response, > just keep in mind that the WiFi router does in fact respond to it, it just > doesn't do so over that bridge port so it didn't get captured on the > gateway's end. "that bridge port"??? Regards Geert Stappers Looking forward to the further information for Subject: Re: [Dnsmasq-discuss] Behavior on DHCP denied -- 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
