Disabling client IP reverse DNS?

Ken Murchison murch at andrew.cmu.edu
Wed Nov 23 07:53:40 EST 2005

Scott Balmos wrote:
> Ken Murchison wrote:
>> Scott Balmos wrote:
>>> Hi all,
>>> I know in a virtual domain setup, if a user connects with an 
>>> unqualified username, the server does a reverse DNS lookup on the 
>>> *server's* incoming connection IP, to determine a default virtual 
>>> domain name.
>>> But how do I disable Cyrus from doing a reverse DNS on the *client's* 
>>> IP that they're connecting from? Connections to my mail server from 
>>> home are taking very long because of a reverse DNS lookup being done 
>>> on my home IP. This fails because my stupid cable Net ISP doesn't 
>>> know how to run DNS properly. :)
>> Set the 'virtdomains' option to 'userid' instead of 1/yes/on.
> This does not solve the situation. I am not in a virtual domain setup. 
> But even with the noted change, the system continues to attempt a 
> reverse DNS on the *client* IP.

Sorry, I didn't read closely enough.  I don't believe there is a way to 
disable this without making changes to the source.  Some SASL mechs 
require the IPs, so we do the lookup before authentication.

Kenneth Murchison
Systems Programmer
Carnegie Mellon University

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