[CLUE-Tech] reverse DNS

[Angelo Bertolli]

Charles Oriez wrote:

> At 12:38 PM 9/10/2004, Angelo Bertolli wrote:
>
>> Even if there is no RDNS, can't you still block based on IP address?  
>> I mean is it now a requirement to have RDNS set up?
>
>
> recommended procedure is to do both.  First step is to refuse 
> connections for invalid RDNS. Second step is to check access.db for 
> local lists of black- or white-listed addresses (for instance, I dont 
> bother checking the blacklists for comcast's SMTP servers, yahoo, aol, 
> etc since virtually no spam comes that way), then check the dnsbls for 
> listed IPA's.
>
> since there is really no technical justification for not having valid 
> rdns on any valid server, requiring rdns to be valid on incoming 
> servers is a simple method to block the many trojaned machines
>
What is considered "valid" ?  Just a response?  Or does it need to match 
the DNS entry for that domain name?

Angelo