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List:       djbdns
Subject:    RE: binding a SOCK_DGRAM to multiple interfaces
From:       "Mike Batchelor" <mdb () ve ! lc ! ro>
Date:       2001-10-04 16:37:14
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> Having dnscache and dnscachex both seems like unneeded duplication.

Yes, they are.  I think the instructions are confusing to a newcomer.  Only
one, or the other is needed.

>
>
> Options:
>
> 1:  run dnscache on the external interface, and make local
> programs use the external interface instead of the faster local
> interface.

It is not slower at all, unless the OS is dumb enough to pass local traffic
needlessly through the ethernet driver.  None that I know of are.

>
> 2:  alter dnscache so that it can bind to both the internal and
> the external interfaces.

It already does:

cd /service/dnscache
echo 0.0.0.0 > env/IP
svc -t /service/dnscache

>
> TCP servers can do this.  Is the problem that a UDP server cannot
> do that because the recvmsg function does not tell you which interface
> the packet arrived at?

There is no problem.  dnscache does just what you want, for both TCP and
UDP.

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