554 SMTP synchronization error
list Dominique Frise
Hi all, Maybe this has been discussed already but I can't find any relevant info. All our smtp tests sporadically report similar error: yellow Wed May 17 14:37:21 2006 smtp NOT ok Service smtp on mailc is not OK : Unexpected service response 554 SMTP synchronization error.. Seconds: 0.00 How can we avoid this? Thanks. Dominique UNIL - University of Lausanne
list Kolbjørn Barmen
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On Wed, 17 May 2006, Dominique Frise wrote:
Hi all, Maybe this has been discussed already but I can't find any relevant info. All our smtp tests sporadically report similar error: yellow Wed May 17 14:37:21 2006 smtp NOT ok Service smtp on mailc is not OK : Unexpected service response 554 SMTP synchronization error.. Seconds: 0.00 How can we avoid this?
I made my own SMTP-tester (to test MX for certain domains, not SMTP on
certain hosts) and there I met this problem. My test is as follows
MXTEST=$((sleep 1 ; echo quit) | nc -w 1 ${MXHOST} 25) || MXCOLOR="red"
Without the sleep, some microsoft servers refused to repond 220, and
without the -w 1 for netcat, some exim servers reponded with the above
554. (IIRC, it might have been the other way around)
I dont really understand why the sleep make any difference, but somehow it
does.
--
Kolbjørn Barmen
UNINETT Driftsenter
list Dominique Frise
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Kolbjørn Barmen wrote:
On Wed, 17 May 2006, Dominique Frise wrote:Hi all, Maybe this has been discussed already but I can't find any relevant info. All our smtp tests sporadically report similar error: yellow Wed May 17 14:37:21 2006 smtp NOT ok Service smtp on mailc is not OK : Unexpected service response 554 SMTP synchronization error.. Seconds: 0.00 How can we avoid this?I made my own SMTP-tester (to test MX for certain domains, not SMTP on certain hosts) and there I met this problem. My test is as follows MXTEST=$((sleep 1 ; echo quit) | nc -w 1 ${MXHOST} 25) || MXCOLOR="red" Without the sleep, some microsoft servers refused to repond 220, and without the -w 1 for netcat, some exim servers reponded with the above 554. (IIRC, it might have been the other way around) I dont really understand why the sleep make any difference, but somehow it does.
After looking deeper into this issue at our site, this error appears only when testing Exim 4.x mail transfer agent. --------extract of Exim 4.30 doc------------ smtp_enforce_sync Type: boolean Default: true The SMTP protocol specification requires the client to wait for a response from the server at certain points in the dialogue. Without PIPELINING these synchronization points are after every command; with PIPELINING they are fewer, but they still exist. Some spamming sites send out a complete set of SMTP commands without waiting for any response. Exim protects against this by rejecting a message if the client has sent further input when it should not have. The error response “554 SMTP synchronization error” is sent, and the connection is dropped. The bbnet-test is to fast! Would it be possible to integrate a -configurable in bb-services- timeout between the connexion established and the data sent by bbnet-test? Dominique UNIL - University of Lausanne
list Henrik Størner
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On Mon, May 29, 2006 at 09:30:07AM +0200, Dominique Frise wrote:
Kolbjørn Barmen wrote:Maybe this has been discussed already but I can't find any relevant info. All our smtp tests sporadically report similar error: yellow Wed May 17 14:37:21 2006 smtp NOT ok Service smtp on mailc is not OK : Unexpected service response 554 SMTP synchronization error..The bbnet-test is to fast! Would it be possible to integrate a -configurable in bb-services- timeout between the connexion established and the data sent by bbnet-test?
The correct solution is to modify the bbtest-net tool to obey the
SMTP protocol, which means waiting for the "220 ..." banner before
sending a QUIT command.
I am planning to rework this in a later version, but for now you can
change the [smtp] section to just avoid sending any data. So in
bb-services it would be
[smtp]
expect "220"
options banner
port 25
The only downside of this is that if you're running sendmail, it
will log a "NOQUEUE" error message each time Hobbit tests it.
Regards,
Henrik
list Dominique Frise
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Henrik Stoerner wrote:
On Mon, May 29, 2006 at 09:30:07AM +0200, Dominique Frise wrote:Kolbjørn Barmen wrote:Maybe this has been discussed already but I can't find any relevant info. All our smtp tests sporadically report similar error: yellow Wed May 17 14:37:21 2006 smtp NOT ok Service smtp on mailc is not OK : Unexpected service response 554 SMTP synchronization error..The bbnet-test is to fast! Would it be possible to integrate a -configurable in bb-services- timeout between the connexion established and the data sent by bbnet-test?The correct solution is to modify the bbtest-net tool to obey the SMTP protocol, which means waiting for the "220 ..." banner before sending a QUIT command. I am planning to rework this in a later version, but for now you can change the [smtp] section to just avoid sending any data. So in bb-services it would be [smtp] expect "220" options banner port 25 The only downside of this is that if you're running sendmail, it will log a "NOQUEUE" error message each time Hobbit tests it. Regards, Henrik
Ok. Thanks a lot for this quick fix. Dominique UNIL - University of Lausanne