[Dnsmasq-discuss] Router Advertisement: Prefix-Specific Options?

[Simon Kelley]

On 16/04/18 14:46, Luis Marsano wrote:
> Hi,
> 
>  
> 
> Apologies if this was answered before.
> 
> In router advertisements, is there a way to declare one prefix
> deprecated without deprecating the others?
> 
>  
> 
> Here’s my situation.
> 
> I’ve been using the dnsmasq option
> 
> dhcp-range=set:lan,::,constructor:br-lan,ra-stateless,ra-names,12h
> 
> to announce a dynamic IPv6 prefix delegated from an ISP, and life was
> beautiful ever since.
> 
> However, my ISP doesn’t delegate reverse DNS, so I obtained an
> additional IPv6 prefix delegated from a tunnel broker.
> 
> Since certain online services block connections from the tunnel broker,
> I’ll need systems to avoid selecting addresses in that prefix as the
> source address when initiating connections.
> 
> According to RFC 6724 <https://tools.ietf.org/html/rfc6724#section-5>,
> announcing addresses in that prefix as deprecated will cause an
> appropriate selection.
> 
> I don’t see an obvious way to selectively deprecate one prefix and not
> others in the manual
> <http://www.thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html>.
> 
> I’ve tried adding the line
> 
> dhcp-range=set:lan,2001:db8::,ra-stateless,ra-names,deprecated
> 
> where /2001:db8::/ would be the prefix delegated from the tunnel broker.
> 
> However,
> 
>   * the router advertises twice, differently
> 
> router advertisement on 2001:db8::
> 
> router advertisement on 2001:db8::, constructed for br-lan
> 
>   * DNS records list addresses from that prefix twice.
> 
> $ dig hostname any
> 
> ;; ANSWER SECTION:
> 
> hostname.           0       IN      A       192.168.0.39
> 
> hostname.           0       IN      AAAA    fd64:cd08:2045::2
> 
> hostname.           0       IN      AAAA    2001:db8::2
> 
> hostname.           0       IN      AAAA    2001:db8::2
> 
>  
> 
> Is there a way to control advertisement options on 1 prefix without
> affecting the others?
> 
> Thanks.
> 
> 

Would this be solved by not constructing a prefix advertisement for
2001:db8:: when it's already explicitly configured?


Cheers,

Simon.


> 
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