1 src 2 dest

[Radel]

Duplicate and resending packets is not sufficent:I'll try to explain: in 
a tcp connection there are some numbers choosen by each host used in the 
3way handshake.
Duiplicating a packet will send 2 syn packets with he same ack numer to 
2 different host. Each host will reply with one ack number. The first 
that reaches the sender host will be accepted and using in the last part 
of the handshake, the other will be discarder because isn't related to 
any known connection (the ack number is not correct...).
This doesn't mean that one mail will be delivered:I think that NO mai 
will be delivered.

Radel

Brad Chapman wrote:

> Mr. Schaaf,
> 
>   Huh? I seemed to have read about a SAME target which allowed you to
> duplicate and resend packets to a different IP address. I believe it
> performs exactly what this guy wants: to be able to deliver multiple
> e-mails to different servers. The only drawback, AFAICE, is that it
> requires multiple rules for multiple e-mail servers; however, AFAIK, this
> multiple-delivery SMTP server you describe could fix that 
> dynamically.....
> 
> Brad
> 
> Patrick Schaaf wrote:
> 
>>> so for example if I had a mail server on the outside of a iptables 
>>> firewall, and I sendmail to this mail server, I want same mail 
>>> delieved to  that server and another mail server aswell.
>> 
>> 
>> 
>> This cannot be done at a packet filtering level. You could use the
>> REDIRECT rules to capture the outgoing SMTP connection, handle it
>> using an SMTP server on the firewall machine, and write this SMTP
>> server in a way that stably feeds each outgoing mail to the two
>> external servers (essentially duplicating the mail, and running
>> two independant deliveries). I don't know of any SMTP server
>> software capable of doing that out of the box, so you probably
>> have to find a knowledgeable programmer who writes it for you.
>> For a competent person, that should 1-2 man-weeks work.
>> 
>> regards
>>   Patrick
>> 
>> 
>> 
> 
>