On 24/03/2019 22:13, Viktor Dukhovni wrote:
On Sun, Mar 24, 2019 at 09:00:24PM +0000, Nick Howitt wrote:
[ Please avoid pasting "non-breaking space" characters into
your email. It is tedious to have to convert these to ASCII. ]
The header is below (x headers and DKIM removed):
Return-Path: <g...@hz.gov.cn>
Received: from hz.cn (unknown [220.191.208.116])
by howitts.co.uk (Postfix) with ESMTP id 6614E401361E
for <usern...@howitts.co.uk>; Sun, 24 Mar 2019 10:09:30 +0000 (GMT)
The "unknown" means that either:
1. The IP did not resolve to a PTR (name) record
2. The name did not resolve back to the same IP
In case 2. the IP could have had a reverse name.
Mar 24 10:09:30 server postfix/smtpd[8102]: warning: hostname
mail.hz.cn does not resolve to address 220.191.208.116
Mar 24 10:09:30 server postfix/smtpd[8102]: connect from
unknown[220.191.208.116]
This is case 2.
Have I misunderstood something or is something else at play?
Inattention to detail, and/or unfamiliarity of the meaning of
"unknown" in the Received header.
Sorry but I am unfamiliar with the term "non-breaking space". Is pasting
from PuTTy or Notepad++ causing an issue?
As far as I can see 220.191.208.116 has no PTR so should fall under your
case 1? Or have I misunderstood?
[root@server ~]# dig -x 220.191.208.116 @8.8.8.8
; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 <<>> -x 220.191.208.116 @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 29403
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;116.208.191.220.in-addr.arpa. IN PTR
;; Query time: 14 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sun Mar 24 22:24:00 GMT 2019
;; MSG SIZE rcvd: 57
