Hello,
I have a VPS running postfix and bind9. Bind is used as a recursive
resolver, in particular to be able to query anti-spam database.
Postfix is also configured to reject incoming connections from servers
with no reverse dns.
It works great overall, but sometimes legitimate messages get rejected
because the reverse dns query fails.
Here is an example (anonymized email and host address):
In mail.log:
450 4.7.1 Client host rejected: cannot find your reverse hostname,
[17.179.250.111]; from=<developer_boun...@insideapple.apple.com>
to=<x...@example.com> proto=ESMTP helo=<rn2-msbadger07105.apple.com>
(total: 1)
In named journal:
mars 02 01:14:20 example.com named[2756114]: client @0x7f3a0808c750
127.0.0.1#43646 (111.250.179.17.in-addr.arpa): query:
111.250.179.17.in-addr.arpa IN PTR +E(0) (127.0.0.1)
mars 02 01:14:25 example.com named[2756114]: client @0x7f3a08079d00
127.0.0.1#43646 (111.250.179.17.in-addr.arpa): query:
111.250.179.17.in-addr.arpa IN PTR +E(0) (127.0.0.1)
mars 02 01:14:32 example.com named[2756114]: client @0x7f3a0808c750
127.0.0.1#43646 (111.250.179.17.in-addr.arpa): query failed (timed out)
for 111.250.179.17.in-addr.arpa/IN/PTR at query.c:6883
mars 02 01:14:32 example.com named[2756114]: client @0x7f3a000d5110
127.0.0.1#49520 (insideapple.apple.com): query: insideapple.apple.com IN
MX + (127.0.0.1)
So there is a timeout.
Now if I try again:
$ dig -x 17.179.250.111 @localhost +short
rn2-msbadger07105.apple.com.
So it seems that it is just that sometimes the query takes a bit longer...
Is there a general advice regarding timeout for bind?
Should I just choose a longer timeout? Or is there a reason for the
default value?
I did not have such problems when I was using the ISP dns server instead
of a local recursive resolver. So I was wondering if the configuration
is sub-optimal somehow...
Thank you,
Cheers,
Julien
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