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Re: is reverse dns required? (policy question)

  • From: Andre Oppermann
  • Date: Fri Dec 03 05:06:04 2004

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.*.*   IN TXT   "0"
_send._smtp._srv.*.*   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
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  It would not be published as such because that obviously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.