Yes, one of my interfaces is fd01::1/64.

I just got it working actually. In my case I have a test lab setup with a
couple networks. The first is a smaller /24 with no ipv6 that is generally
accessible in my company. The second is a /16 using the 198.18/15 address
space for testing with the fd01::/64 ipv6 addressing. Originally I had two
dnsmasq configurations to provide DNS/DHCP (1 per network). When I switched
over to a single configuration with all the dhcp-option, dhcp-range
configurations including the network interface they should be applicable
to, things just started working. I am not sure why it helped but either way
I would rather have a single configuration anyways.

Matthew Keeler

On January 23, 2018 at 12:18:47, Erik Nordmark ( wrote:

On 01/22/2018 02:27 AM, Andy Hawkins wrote:
> Hi,
> In article <>,
> Simon Kelley<> wrote:
>> Do you have an interface configured with an address in fd01::/64 ?
> Is this a requirement? radvd is able to send advertisements out on an
> interface that has no IPv6 address configured (indeed, I have been using
> this facility to automatically configure the interface that router
> advertisements are being sent on).
> Would be nice to be able to do the same with dnsmasq without having to
> manually configure the IPv6 address of the interface.


I've run into this limitation as well, due to using the "no on-link
prefixes" option in neighbor discovery (meaning that I use dhcpv6 for
address assignment, and radvd doesn't advertise any onlink prefix).

This means I don't have a /64 prefix configured on any interface which
matches the range from which dnsmasq assigns IPv6 addresses.

My workaround is to remove the /64 check from dnsmasq (see below). I've
been meaning to discuss this on the list.


diff -r -u ../dnsmasq-orig/dnsmasq-2.75/src/option.c src/option.c
--- ../dnsmasq-orig/dnsmasq-2.75/src/option.c 2015-07-30
12:59:07.000000000 -0
+++ src/option.c 2017-06-13 15:14:58.109166818 -0700
@@ -2734,9 +2734,6 @@
ret_err(_("prefix length must be exactly 64 for subnet constru

- if (new->prefix < 64)
- ret_err(_("prefix length must be at least 64"));
if (!is_same_net6(&new->start6, &new->end6, new->prefix))
ret_err(_("inconsistent DHCPv6 range"));

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