On Nov 5, 2009, at 16:12, Eric B. wrote:
"Daniel L'Hommedieu" <dlhommed...@gmail.com> wrote in message
news:670a051c-1871-4e2e-82d8-187324ef1...@gmail.com...
On Nov 5, 2009, at 15:52, Eric B. wrote:
"Eric B." <ebe...@hotmail.com> wrote in message
news:hcupsk$b8...@ger.gmane.org...
"Victor Duchovni" <victor.ducho...@morganstanley.com> wrote in
message
news:20091104232940.gi27...@np305c2n2.ms.com...
On Wed, Nov 04, 2009 at 06:16:56PM -0500, Eric B. wrote:
Is there no way to direct Postfix to a different DNS server (as
opposed
to
the ones specified in resolve.conf) either for a particular
domain,
or
for
all domains altogether?
If you chroot-jail the smtp(8) delivery agent, it will use the
resolv.conf
file in the chroot jail. This is ugly, you are probably solving
the
wrong problem.
Interesting thought. I agree that this is somewhat ugly, but
might be
something worth investigating...
Ok - now I am very confused. I tried setting up Postfix in a chroot
jail,
and specified a different set of nameservers in
/var/spool/postfix/etc/resolv.conf. However, it seems as though
Postfix
continues to use the name servers specified in /etc/resolv.conf
and not
the
ones in the chroot jail.
I have gone so far as to create an empty /var/spool/.../
resolv.conf with
no
nameservers specified, and yet postfix is still able to deliver the
email
(to the wrong server). I would have expected that leaving the
nameservers
blank would have caused Postfix to choke, and yet it still connects.
I definitley have chroot set to Y in my master.cf file, and have
done a
postfix restart. I do get a warning on restart that
postfix/postfix-script: warning: /var/spool/postfix/etc/
resolv.conf and
/etc/resolv.conf differ
Or does the fact that they differ cause the chroot to fail, and the
process
ends up running in regular mode instead?
I have gone as far as deleting the /var/spool/postfix/lib and lib64
directories, and postfix still starts without any error
messages. And
when
I try to mail something, it still manages to send the mail. So that
gives
me confirmation that the chroot isn't working properly.
Apart from setting chroot to y in master.cf, is there anything
else I
have
to do to enable it properly?
Thanks,
Eric,
Getting back to your original goal, my understanding is that the
original
goal is to override the DNS "A" record for a single host, yes? If
so,
that is a perfect use for /etc/hosts. Give that method a try.
Actually, it isn't for the "A" record; it is for the MX record(s).
And
unfortunately, I know of no way of using the hosts file to override MX
records for a particular domain.
Thanks,
Eric
Eric,
Redirected back on-list.
It seems to me that you do want to override an "A" record: all you
care about is that outbound mail gets routed through another host.
Your postfix server will use DNS to query for the MX record for example.com
, which will return mx.example.com. Ordinarily it would then query
DNS for the "A" record for mx.example.com, but if you configure nsswitch.com
to query files before DNS, you can put mx.example.com into the /etc/
hosts file, with the desired IP address.
Daniel
