Re: mapping dynamic IPs to specific accounts

[Miles Fidelman]

Mike Kenny wrote:
A client of mine provides an email service to a number of mobile 
users. This leave my client open to abuse as addresses are assigned 
dynamically and blocking specific users is difficult. We have set up 
an internal, private DNS which we update with the authentication 
details of the user and the IP assigned to him/her at that  time. We 
now want to configure postfix/spamassassin to query this DNS and 
return the authentication details. This will allow us to blacklist the 
abusive users until they re-register (at a cost) and should help us 
fight the proliferation of spam.

How best can this be done? It is not enough that the IP is in the DNS, 
we expect it to be and we don not want to blacklist based on the IP. 
We actually need to get the authentication details back and look these 
up in a blacklist. So how do we configure postfix or spamassassin to 
look up 
Mike,

You're barking up the wrong tree.  There are several well-established 
mechanisms specifically designed to authenticate mobile users to email 
systems.  What you want is SMTP AUTH, possibly w/ TLS.  Look at the 
wikipedia entries for SMTP-AUTH and SASL, and then look at the Postfix 
howtos.

Miles Fidelman