Re: reverse lookup validation failed - how do I fix this?

On Mon, 31 Mar 2025 04:58:28 -0400 (EDT)
Claus Aßmann
<INVALID_NO_CC_REMOVE_IF_YOU_DO_NOT_POST_ml+sendmail(-no-copies-please)@esmtp.org>
wrote:

Nigel Reed  wrote:
 

Mar 31 02:01:39 newsfeed nnrpd[3339866]: ? reverse lookup for
2001:41d0:a:280::1 failed: reverse lookup validation failed --
using IP address for access 

 

Interestingly, news.nntp4.net does not resolve back to that IP, it
uses 2001:41d0:700:1273:: 

 
That's probably why the "reverse lookup validation failed"
otherwise someone could map their IP to any name they like
to get around hostname based access control.
 
MTAs have done that kind of check "for ages".
 
BTW: does the DNS resolver used by nnrpd give the expected
result for your own IP?

I'm pretty sure I said in the original message that my IP resolves
correctly. You seem to have ignored that paragraph.


news@newsfeed:~$ host 2602:fe64:8::7
7.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.0.0.0.4.6.e.f.2.0.6.2.ip6.arpa
domain name pointer newsfeed.endofthelinebbs.com.

news@newsfeed:~$ host newsfeed.endofthelinebbs.com
newsfeed.endofthelinebbs.com has address 144.172.126.95
newsfeed.endofthelinebbs.com has IPv6 address 2602:fe64:8::7

news@newsfeed:~$ host 144.172.126.95
95.126.172.144.in-addr.arpa domain name pointer
newsfeed.endofthelinebbs.com.


All my IPs resolve correctly.




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