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Re: Snapshot 20130517

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  • /dev/rob0
    ... For testing I reenabled PSBL, and I ll see what comes in overnight. I thought I could make my own pseudo-DNSBL on a random IP address with blocked ports
    Message 1 of 25 , May 17, 2013
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      On Fri, May 17, 2013 at 10:06:38PM -0400, Wietse Venema wrote:
      > Wietse Venema:
      > > I can change postscreen to also use partial scores for
      > > whitelisting of non-DNS tests, and thereby make whitelisting
      > > of non-DNS tests consistent with DNS-based blocking (that's one
      > > less WTF factor). This requires minor code duplication.
      >
      > Released as snapshot 20130517.

      For testing I reenabled PSBL, and I'll see what comes in overnight.
      I thought I could make my own pseudo-DNSBL on a random IP address
      with blocked ports 53, but I need to set up an NS record to point to
      that. I'll do that tomorrow if results tonight are inconclusive.
      --
      http://rob0.nodns4.us/ -- system administration and consulting
      Offlist GMX mail is seen only if "/dev/rob0" is in the Subject:
    • Wietse Venema
      ... For whitelisting I used a wild-card A record, and for timeout testing I used an NS record that resolves to a firewalled port (a black hole). This
      Message 2 of 25 , May 18, 2013
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        /dev/rob0:
        > On Fri, May 17, 2013 at 10:06:38PM -0400, Wietse Venema wrote:
        > > Wietse Venema:
        > > > I can change postscreen to also use partial scores for
        > > > whitelisting of non-DNS tests, and thereby make whitelisting
        > > > of non-DNS tests consistent with DNS-based blocking (that's one
        > > > less WTF factor). This requires minor code duplication.
        > >
        > > Released as snapshot 20130517.
        >
        > For testing I reenabled PSBL, and I'll see what comes in overnight.
        > I thought I could make my own pseudo-DNSBL on a random IP address
        > with blocked ports 53, but I need to set up an NS record to point to
        > that. I'll do that tomorrow if results tonight are inconclusive.

        For whitelisting I used a wild-card "A" record, and for timeout
        testing I used an NS record that resolves to a firewalled port (a
        black hole).

        This confirmed that postscreen will now use partial scores to
        whitelist pending non-dnbsbl tests.

        I can make those domain names available for general testing (but
        not now as I am in the middle of a copper-to-fiber conversion).

        Wietse
      • /dev/rob0
        Still watching logs, this one just passed by. Probably unrelated to the changes in 20130517, but I was curious about it: May 19 13:24:20 harrier
        Message 3 of 25 , May 19, 2013
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          Still watching logs, this one just passed by. Probably unrelated to
          the changes in 20130517, but I was curious about it:

          May 19 13:24:20 harrier postfix/postscreen[3533]: CONNECT from [188.42.15.19]:48706 to [207.223.116.211]:25
          May 19 13:24:26 harrier postfix/postscreen[3533]: NOQUEUE: reject: RCPT from [188.42.15.19]:48706: 450 4.3.2 Service currently unavailable; from=<bounce@...>, to=<munged@...>, proto=ESMTP, helo=<mail18.consumer-news123.com>
          May 19 13:24:26 harrier postfix/postscreen[3533]: PASS NEW [188.42.15.19]:48706
          May 19 13:24:26 harrier postfix/postscreen[3533]: DISCONNECT [188.42.15.19]:48706

          All is well and good for a non-whitelisted host, but apparently it
          was too quick in coming back to the secondary MX IP address ...

          May 19 13:24:26 harrier postfix/postscreen[3533]: CONNECT from [188.42.15.9]:33610 to [207.223.116.214]:25
          May 19 13:24:26 harrier postfix/postscreen[3533]: WHITELIST VETO [188.42.15.9]:33610

          ... all in the same second, but according to syslog, sequentially
          after having earned whitelist status.

          May 19 13:24:32 harrier postfix/postscreen[3533]: NOQUEUE: reject: RCPT from [188.42.15.9]:33610: 450 4.3.2 Service currently unavailable; from=<bounce@...>, to=<munged@...>, proto=ESMTP, helo=<mail8.consumer-news123.com>
          May 19 13:24:32 harrier postfix/postscreen[3533]: DISCONNECT [188.42.15.9]:33610

          Another six seconds pass before this one is turned away, which
          suggests that the greet pause was repeated. Makes sense, because
          "WHITELIST VETO" means it was not seen before.
          --
          http://rob0.nodns4.us/ -- system administration and consulting
          Offlist GMX mail is seen only if "/dev/rob0" is in the Subject:
        • Wietse Venema
          ... postscreen does not find the client IP address in the permanent postscreen_access_list, does not find client the IP address in the temporary
          Message 4 of 25 , May 19, 2013
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            /dev/rob0:
            > Still watching logs, this one just passed by. Probably unrelated to
            > the changes in 20130517, but I was curious about it:
            >
            > May 19 13:24:20 harrier postfix/postscreen[3533]: CONNECT from [188.42.15.19]:48706 to [207.223.116.211]:25
            > May 19 13:24:26 harrier postfix/postscreen[3533]: NOQUEUE: reject: RCPT from [188.42.15.19]:48706: 450 4.3.2 Service currently unavailable; from=<bounce@...>, to=<munged@...>, proto=ESMTP, helo=<mail18.consumer-news123.com>
            > May 19 13:24:26 harrier postfix/postscreen[3533]: PASS NEW [188.42.15.19]:48706
            > May 19 13:24:26 harrier postfix/postscreen[3533]: DISCONNECT [188.42.15.19]:48706

            postscreen does not find the client IP address in the permanent
            postscreen_access_list, does not find client the IP address in the
            temporary postscreen_cache_map, logs the "all tests passed" status,
            updates the temporary postscreen_cache_map with the expiration time
            for each test, and forgets the test results.

            > All is well and good for a non-whitelisted host, but apparently it
            > was too quick in coming back to the secondary MX IP address ...
            >
            > May 19 13:24:26 harrier postfix/postscreen[3533]: CONNECT from [188.42.15.9]:33610 to [207.223.116.214]:25
            > May 19 13:24:26 harrier postfix/postscreen[3533]: WHITELIST VETO [188.42.15.9]:33610
            >
            > ... all in the same second, but according to syslog, sequentially
            > after having earned whitelist status.

            postscreen logs "CONNECT from", does not find the client IP address
            in the permanent postscreen_access_list, and does not find the
            client IP address in the temporary postscreen_cache_map. Therefore
            this is handled as a non-whitelisted client that connects to the
            "wrong" IP address.

            Why wasn't the client IP address found in the temporary
            postscreen_cache_map? Maybe silent corruption of the cache database.

            Wietse
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