[Unbound-users] DNS multiplexer?

Carsten Strotmann unbound at strotmann.de
Wed Aug 11 14:30:33 UTC 2010

 On 8/11/10 2:59 PM, João Damas wrote:
> Does anyone know of any code that will let one to run Unbound and NSD on the same IP address and still use port 53 for listening on both?
> Something like a DNS multiplexer front end, so that the recursive server and the authoritative server are kept separate but the front-end directs queries to one or the other (either based on the RD bit, a locally configured list of zones, e.g. from NSD config, or some other way). Something that is lightweight but avoids having to burn additional IP addresses.
> Thanks
> Joao
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Hello Joao,

I'm not aware of an stand-alone multiplexer. I was looking for a similar
solution in the past to be able to run unbound and BIND (authoritative
only, with dynamic DNS zones) on the same physical machine in my home
network. First I had a setup similar to what Patrik is suggesting
(unbound on port 53, forwarding local zones to a BIND DNS running on
port 15353).

        name: "home.strotmann.de"

However that did not work well with dynamic updates, because there is no
way (to my knowledge) to forward dynamic updates from unbound to a
different server/port.

In my current setup I have two IP Addresses on the same NIC on the
server machine, have unbound listen on the 1st ( and BIND on
the 2nd ( Unbound is forwarding all request for local
domains to the 2nd IP address on the same physical server box.

        name: "home.strotmann.de"

So unbound works like kind of a multiplexer based on the dns name in the

However this is not a recommended setup in a production environment, but
works fine in my little home network.

-- Carsten

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