[Mimedefang] Blocking Dictionary Attacks

John Nemeth jnemeth at victoria.tc.ca
Fri Jun 5 04:06:33 EDT 2009

On Oct 25,  4:06pm, afo cliff wrote:
} That's a great idea!  I tried it but no matter what I do, sendmail is
} letting everything through.  Virtusertable is configured correctly in
} sendmail.mc, also did the appropriate makemap.  I think something has
} changed in sendmail (I have 8.13.8).  I've searched the world over 10
} times and tried many different combinations in virtusertable &
} mailertable and no matter what it relays everything.  I know it is

     When asking for help, it would be helpful if you gave details of
your setup.  It sounds like you have sendmail+mimedefang front ending
other mail servers.  There are a few ways to solve this problem.  One
is the virtuser method mentioned previously.  Another is to use LDAP.
If you also use LDAP for your account info then you only have to
maintain the information in one place.  See the sendmail manual for
information on this option.  Another one which can work well if the
downstream servers are close by, reliably up, and respond quickly is to
have MIMEDefang query the downstream server and return a result based
on that.  See "REJECTING UNKNOWN USERS EARLY" in 'man mimedefang-filter'.

}-- End of excerpt from afo cliff

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