[Dnsmasq-discuss] REFUSED after dropped packets

Johannes Stezenbach js at sig21.net
Tue Sep 28 17:08:19 UTC 2021


On Mon, Sep 27, 2021 at 10:45:25PM +0100, Simon Kelley wrote:
> 
> I think that this is a 2.86 problem. There are two cases when dnsmasq
> will try another server with the same query:
> 
> 1) When a client retries the query.
> 2) When the first server returns REFUSED.
> 
> In the second case, it's important to give up when all available servers
> have returned REFUSED, otherwise the query keeps bouncing forever. 2.86
> got the two cases mixed up and implemented that behavior for client
> retries too. That's a bug.
> 
> https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=2561f9fe0eb9c0be1df48da1e2bd3d3feaa138c2
> 
> should fix it.
> 
> 
> Please test.....

This seems to work well. Currently my Wifi connection is stable,
thus I disconnected the antenna to simulate the problem:

$ host kernel.org
;; connection timed out; no servers could be reached

Dnsmasq properly forwarded the client retry:

Sep 28 19:00:03 dnsmasq[32598]: 4 127.0.0.1/35962 query[A] kernel.org from 127.0.0.1
Sep 28 19:00:03 dnsmasq[32598]: 4 127.0.0.1/35962 forwarded kernel.org to 192.168.178.1
Sep 28 19:00:08 dnsmasq[32598]: 5 127.0.0.1/35962 query[A] kernel.org from 127.0.0.1
Sep 28 19:00:08 dnsmasq[32598]: 5 127.0.0.1/35962 forwarded kernel.org to 192.168.178.1


After reattaching the antenna:

$ host kernel.org
kernel.org has address 198.145.29.83
kernel.org mail is handled by 10 mail.kernel.org.

Sep 28 19:00:51 dnsmasq[32598]: 6 127.0.0.1/54047 query[A] kernel.org from 127.0.0.1
Sep 28 19:00:51 dnsmasq[32598]: 6 127.0.0.1/54047 forwarded kernel.org to 192.168.178.1
Sep 28 19:00:51 dnsmasq[32598]: 6 127.0.0.1/35962 reply kernel.org is 198.145.29.83
Sep 28 19:00:51 dnsmasq[32598]: 6 127.0.0.1/54047 reply query is duplicate
Sep 28 19:00:51 dnsmasq[32598]: 7 127.0.0.1/41845 query[AAAA] kernel.org from 127.0.0.1
Sep 28 19:00:51 dnsmasq[32598]: 7 127.0.0.1/41845 forwarded kernel.org to 192.168.178.1
Sep 28 19:00:51 dnsmasq[32598]: 7 127.0.0.1/41845 reply kernel.org is NODATA-IPv6
Sep 28 19:00:51 dnsmasq[32598]: 8 127.0.0.1/42436 query[MX] kernel.org from 127.0.0.1
Sep 28 19:00:51 dnsmasq[32598]: 8 127.0.0.1/42436 forwarded kernel.org to 192.168.178.1
Sep 28 19:00:51 dnsmasq[32598]: 8 127.0.0.1/42436 reply kernel.org is <MX>


Thanks,
Johannes



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