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

Luis Marsano luis.marsano at gmail.com
Mon Apr 16 14:46:04 BST 2018


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.

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