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Re: is reverse dns required? (policy question)
Mark Andrews wrote:
In article <[email protected]> you write:You would put in a global wildcard that says no smtp sender here. Only for those boxes being legitimate SMTP to outside senders you'd put in a more specific record as shown above. You probably have to enter some dozen to one hundred servers this way. Sure your reverse zone scripts need some changes but it's only two or three lines. Ideally you could tell your DNS server in the zone file this: _send._smtp._srv.*.*.173.128.in-addr.arpa. IN TXT "0" _send._smtp._srv.*.*.82.198.in-addr.arpa. IN TXT "0" being overidden by more specific information on single IP addresses.You obviouly do not know how wildcard work in the DNS or you would not have made this suggestion. Please read RFC 1034 and work though Section 4.3.2. Algorithm with a QNAME of _send._smtp._srv.184.108.40.206.in-addr.arpa.
The wildcards are in the DNS server zone file for interpretation by the DNS server itself. It would not be published as such because that obviously wouldn't work as you prove. But nothing is preventing BIND or whatever from taking this wildcard record and answering every request with the wildcard "_send._smtp._srv.*" RR if no more-specific exists. This should be relatively straight forward to code. Wouldn't want to touch the code base of BIND but for DJBDNS I could somewhat easily implement it. -- Andre