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Re: smtpd error sleep time

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  • motty cruz
    Thank you very much! you explaining very well! I will close my eyes in this case. Thanks very much again! -Motty
    Message 1 of 5 , Dec 21, 2012
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      Thank you very much! you explaining very well! I will close my eyes in this case.

      Thanks very much again!
      -Motty

      On Fri, Dec 21, 2012 at 10:07 AM, Noel Jones <njones@...> wrote:
      On 12/21/2012 11:25 AM, motty cruz wrote:
      > Hello,
      > I have the following in my configuration but does not seem to make
      > any difference on the connection errors I see in the logs
      >
      > smtpd_error_sleep_time=1h

      The above is a good way to DoS yourself.  Error sleep time should be
      0s or 1s, never more than a few seconds.  This has nothing to do
      with your log snippet below.

      > smtpd_soft_error_limit=10
      > smtpd_hard_error_limit=20


      Those are OK, but have nothing to do with your log snippet below.


      >
      >
      > log:
      > Dec 21 09:22:53 mas postfix/smtpd[23941]: connect from
      > unknown[186.81.31.93]
      > Dec 21 09:22:54 mas postfix/smtpd[23941]: NOQUEUE: reject: RCPT from
      > unknown[186.81.31.93]: 554 5.7.1 Client host rejected: cannot find
      > your hostname, [186.81.31.93]; from=<KG.830@...
      > <mailto:KG.830@...>> to=<jason_griffin@...
      > <mailto:jason_griffin@...>> proto=SMTP helo=<lincoln.com
      > <http://lincoln.com>>
      > Dec 21 09:22:54 mas postfix/smtpd[23941]: lost connection after RCPT
      > from unknown[186.81.31.93]
      > Dec 21 09:22:54 mas postfix/smtpd[23941]: disconnect from
      > unknown[186.81.31.93]
      >
      > it's been going for about an hour and it does not stop, any idea?

      It's unclear what you want to stop.  The above client was rejected
      with the "reject_unknown_client_hostname" restriction.  The
      rejection is correct as the client hostname does not have a matching
      A record. (name->address mapping failed).
      http://www.postfix.org/postconf.5.html#reject_unknown_client_hostname

      The client is also listed on several RBLs.  If your intention is to
      stop seeing rejections from this client in your logs, either close
      your eyes, or firewall the IP.  Unless you're getting enough
      connections from this client to constitute a DoS attack, it's not
      bothering postfix in the least, and not accepting any mail from the
      offending client.

      If your intention is to temporarily block a persistent spammer, use
      fail2ban.



        -- Noel Jones

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