[Dnsmasq-discuss] IP6 DNS UDP strange behaviour

Roger James roger at beardandsandals.co.uk
Tue Jun 27 06:56:32 BST 2017

I am seeing some rather perplexing behaviour regarding the reception of 
upstream IPV6 UDP DNS query responses on a Debian (raspian) system running 
on a Raspberry Pi. It appears that dnsmasq is not holding open an IPV6 UDP 
port to handle a response to an upstream query. What my network monitor 
shows is the upstream request going out and a reply coming back in. However 
the Pi rejects the incoming UDP packet with a ICMPV6 Destination 
unreachable (port unreachable).

I may be missing something obvious here, but it looks like dnsmasq is not 
holding open a listening port for the response.

Has anyone got any ideas on what is going, or can point me at some ways of 
tracking this down.

The configuration of dnsmasq is out of the box Debian.



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