Re: lame reverse DNS?

On Thu, Feb 27, 2020 at 10:31:59AM +0100, Kurt Jaeger wrote:
> Hi!
> 
> > The problem has been resolved but I still sometimes see "connect from
> > unknown[2610:1c1:1:606c::19:2]" in the maillog (today: 6 of 131
> > connections). Local unbound issue?
> 
> That IPv6 has a valid reverse DNS record, so please try to investigate.

Yes, I know. Otherwise it would fail permanently.

- Postfix sends two standard queries (PTR) to local unbound within 5
seconds (05:51:23 and 05:51:28)
- Unbound sends multiple queries to 2610:1c0::1104 and 2610:1c0::1204
without receiving a reply (05:51:23 - 05:51:41)
- Unbound replies twice with Server failure (05:51:53)

I have this issue only with [2610:1c1:1:606c::19:2]:

# grep " connect from unknown" /var/log/maillog
Feb 27 03:37:53 mail postfix/smtpd[93921]: connect from unknown[2610:1c1:1:606c::19:2]
Feb 27 08:40:27 mail postfix/smtpd[33354]: connect from unknown[2610:1c1:1:606c::19:2]
Feb 27 09:43:39 mail postfix/smtpd[41982]: connect from unknown[2610:1c1:1:606c::19:2]
Feb 27 10:53:38 mail postfix/smtpd[4960]: connect from unknown[2610:1c1:1:606c::19:2]
Feb 27 15:30:28 mail postfix/smtpd[87816]: connect from unknown[2610:1c1:1:606c::19:2]
Feb 27 15:50:30 mail postfix/smtpd[98816]: connect from unknown[2610:1c1:1:606c::19:2]

I've already set cache-min-ttl to 3600. FreeBSD.org uses ttl=60. Why?
I'll try to set do-ip6=no. Meanwhile I've whitelisted the IPv6 address
in postfix. 

-- 
Herbert