[Dnsmasq-discuss] Is dnsmasq supposed to listen on UDP port 0.0.0.0:67 when listen-address is specified?

Ignat Korchagin ignat at cloudflare.com
Fri Dec 22 12:10:03 GMT 2017


I think so as well. It may create issues when someone runs 2 dnsmasq
processes with different configurations (for different interfaces for
example - 1 dnsmasq process per interface). Kernel may "balance" incoming
UDP packets to another dnsmasq instance (which AFAIR will just ignore it),
so there will be more retries in general for DHCP traffic.

On Fri, Dec 22, 2017 at 2:46 AM, Parke <parke.nexus at gmail.com> wrote:

> On Thu, Dec 21, 2017 at 2:56 AM, Ignat Korchagin <ignat at cloudflare.com>
> wrote:
> > FYI a good overview of SO_REUSEPORT at least in Linux is here
> > https://blog.cloudflare.com/the-sad-state-of-linux-socket-balancing/
>
> Thanks.  The article deals with accepting on a TCP socket, not
> receiving on a UDP socket.
>
> But if the principles are similar for UDP, then, as I expected, it
> looks like SO_REUSEPORT provides load balancing.
>
> Does anyone believe that dnsmasq is intending to create load balancing
> when multiple instances bind to the same DHCP socket?  (I don't.  I
> believe dnsmasq is expecting mirroring, but I could be wrong.)
>
> Cheers,
>
> Parke
>
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