So, the packets don't go to the DNS servers to be forwarded?
by seanferd
In reply to
Kindle WiFi IP Stack Erro ...
Kindle WiFi IP Stack Error
We recently received a new Kindle WiFi (the $139 version). It would not connect to our WiFi network. Other computers and devices could connect and access the Internet. After several attempts, including completely disabling WiFi security in the access point, we had no luck. To test the Kindle we took it to Starbucks -- it worked fine there.
Back home. We didn't get any useful help from Amazon's Kindle support so I started digging through network logs. It turns out the Kindle was actually connecting. The DHCP server log showed it getting an IP address (192.168.1.93) along with the gateway (192.168.1.1) and DNS server addresses (192.168.1.5 and 192.168.1.6).
I put a network sniffer between the WiFi access point and the network. The DHCP packets showed the Kindle connecting. After the Kindle connected, it used ARP to obtain the MAC address of the gateway. Then it started flooding the network with DNS requests for dns.kindle.com and a server in the cloudfront.net domain. There were no reply packets from the DNS servers.
Our DNS servers were working for other devices but had no log entry for the Kindle's request. A close inspection of the Kindle DNS request packets revealed that it was sending them to the correct IP addresses for the DNS servers but was directing them to the MAC address of the gateway rather than the MAC addresses of the DNS servers. Since the packets could not be routed to the Internet, the gateway dropped them.
It appears that the Kindle stack implementation assumes that all DNS packets should be sent to the gateway. This works in nearly all home networks and most public WiFi hotspots because the wireless router is either a proxy for DNS or the DNS servers are located on the Internet side of the WiFi router. Many business networks would have local DNS servers as described here.
My workaround was to manually configure the Kindle to use an external DNS server provided by our ISP. You could also use one at openDNS. The configuration can be set through the Kindle keyboard or DHCP can be configured to deliver the settings based on the Kindle MAC address.
Hopefully Amazon will fix this with a software update since the workaround can only be used when you know a safe IP address to manually configure for the Kindle.
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