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Re: postfix security configuration



This might help:


http://jimsun.linxnet.com/misc/postfix-anti-UCE.txt

On Mon, 2003-08-11 at 13:37, Marcel Weber wrote:
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> Am Montag, 11.08.03, um 12:59 Uhr (Europe/Zurich) schrieb Tomasz 
> Papszun:
> >>
> >
> > If you want to prevent them from using non existing sender addresses
> > from your domain, you can do it by creating a file (lookup table) for
> > postmap(1), containing all allowed addresses with "OK" and another
> > table containing your domainname with "REJECT".
> >
> > If you want to prevent them from using sender addresses from other
> > domain, it's also possible with properly prepared config.
> >
> > If you want to prevent them from using other (not their own) sender
> > addresses from your domain, you must use SMTP AUTH, I'm afraid.
> >
> > -- 
> >  Tomasz Papszun   SysAdm @ TP S.A. Lodz, Poland  | And it's only
> >  tomek@lodz.tpsa.pl   http://www.lodz.tpsa.pl/   | ones and zeros.
> >
> >
> > -- 
> > To UNSUBSCRIBE, email to debian-security-request@lists.debian.org
> > with a subject of "unsubscribe". Trouble? Contact 
> > listmaster@lists.debian.org
> >
> 
> Theoretically there is another possibility. Actually pop-before-smtp 
> does nothing than watching the log file, picking the ip address of the 
> pop client and putting this address for a certain time into a postmap 
> for postfix. If you would use the user's email address as his pop3 
> login name (within a sql or ldap db, for example), one could take this 
> information and write it into another postmap file. This would 
> necessite some modification of the pop-before-smtp script, but I think 
> it wouldn't be too hard to implement. It wouldn't be perfect, though: 
> Imagine two users logged in at the same time. Under this situation each 
> user could "abuse" the other user's email address.
> 
> For a really secure system, there is no way around smtp auth. 
> pop-before-smtp relies on ip addresses. But what about NAT? Users 
> coming from a private masqueraded network, could misuse your server at 
> their pleasure, if one user from this network has logged into his pop3 
> account.
> 
> Regards
> 
> Marcel
> 
> 
> 
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