On Mon, Jun 27, 2005 at 09:38:15AM +0100, Philip Hazel wrote:
> (b) Watching the actual network packets with tcpdump, so you can see
> what is actually happening.
Ok, I got a friend to help me out, and was about to reproduce this bug
in a his server too, he is running Exim 4.42:
Architecture:
2ndMX: This server is a secondary MX with priority 40 for a domain.
There is a priority 10 MX for this domain, which has a 10 second
delay before presenting the banner.
1stMX: This is the primary MX for the domain. This has a 10 second
delay before the banner. Any host sending data before the banned
/ 220 is displayed will get an SMTP Protocol Violation,
Synchronization Error
Sender: This is and end user machine, sending email to the domain.
ACL's: The 2ndMX machine, has the following callout ACL:
verify = recipient/callout=10s,defer_ok
This ACL should cause the 2ndMX to connect to the 1stMX, when it
receives a message for the domain, to verify the recipient
exists.
Test method:
Telnet from "Sender" to "2ndMX" on port 25, and simulate an SMTP
conversation.
Results:
This dialog shows the conversations between "Sender" and "2ndMX", and
the callout from "2ndMX" to "1stMX" in the middle. The bizarrest thing
seems to be, when the "2ndMX" is supposed to do the called, all it is
doing is connecting to the "1stMX" and sending QUIT:
2ndMX: 220 2ndMX.host.name ESMTP Exim 4.42 Wed, 20 Jul 2005 11:14:02 +0100
Sender: HELO sender.host.name
2ndMX: 250 2ndMX.host.name Hello sender.host.name [sender.ip.address]
Sender: MAIL FROM: <>
2ndMX: 250 OK
Sender: RCPT TO: <user@???>
2ndMX: 250 Accepted
1stMX: QUIT
Sender: 554 SMTP synchronization error
Sender: QUIT
2ndMX: 221 2ndMX.host.name closing connection
--
Avleen Vig
Systems Administrator
Doing virtual domain hosting with Exim?
Check out Virtual Exim: http://silverwraith.com/vexim
(Click the banner, support development..)
