[Dnsmasq-discuss] Sending RA without dhcp-range

Simon Kelley simon at thekelleys.org.uk
Fri Jan 17 10:49:00 GMT 2014


On 17/01/14 06:10, Albert ARIBAUD wrote:
> Le 17/01/2014 05:30, Shixiong Shang a écrit :
>> Hi, experts:
>>
>> Is it possible that dnsmasq can send out RA with either A=0, MO=1
>> (i.e. for DHCPv6 Stateful), or AO=1, M=0 (i.e. for DHCPv6 Stateless)
>> WITHOUT dhcp-range? What I am trying to achieve here is using dnsmasq
>> to send out RA to trigger DHCPv6 Stateful or DHCPv6 Stateless mode
>> without acting as DHCPv6 server. Based on my reading, I am under the
>> impression that “—enable-ra” must be used with “—dhcp-range”.
>> Otherwise, dnsmasq will not send RA…..
>
> You are right about having to add enable-ra.
>
> However there is a syntax of dhcp-range which will not cause DHCPv6.
>
> As per 'man dnsmasq' (search for 'dhcp-range'), the possible modes for
> IPv6 ranges include 'ra-only', which will previsely enable RAs without
> enabling any DHCP.
>

Neither of you are completely right.

enable-ra causes RA with A=0 and M = 1  O = 1 on every interface that's 
doing DHCP, just to instruct the clients to do stateful DHCP. It's 
intended as a simple option for systems which don't use RA at all.

You don't need to set enable-ra at all to do RA on specific interfaces 
with other flag combinations, ie

ra-only A=1 M=0 O=0
slaac   A=1 M=1 O=1
ra-stateless A=1 M=0 O=1

Cheers,

Simon.







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