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Re: Creating exceptions to greylisting

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  • James Griffin
    ... It s actually very easy to upgrade your Postfix installation by compiling the source code. I have needed to do it numerous times, it s worth getting into
    Message 1 of 13 , Feb 2, 2013
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      --> Gerben Wierda <gerben.wierda@...> [2013-02-02 19:37:41 +0100]:

      > Actually, I'm still on /usr/libexec/postfix/greylist.pl
      > as I am using Mac OS X Server 10.6.8 and I haven't dared to upgrade
      > to a higher version of OS X Server as they were busy crippling it
      > in many respects.

      It's actually very easy to upgrade your Postfix installation by
      compiling the source code. I have needed to do it numerous times,
      it's worth getting into the habit of upgrading in this way if you're
      using internet servers.

      You can also use the Macports system. It will provide a way for you
      to use the newer Macports Postfix and stop the Apple installed
      Postfix using launchctl. It's all automated and practically idiot
      proof.


      --
      Primary Key: 4096R/1D31DC38 2011-12-03
      Key Fingerprint: A4B9 E875 A18C 6E11 F46D B788 BEE6 1251 1D31 DC38
    • Gerben Wierda
      Just so there is no misunderstanding: I am unhappy running an older version that is not updated with security fixes anymore and I had planned to upgrade before
      Message 2 of 13 , Feb 2, 2013
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        Just so there is no misunderstanding: I am unhappy running an older version that is not updated with security fixes anymore and I had planned to upgrade before now (but not immediately when 10.8 came out as 10.8.0 Server was not what you say trustworthy. I skipped 10.7 server altogether because it is a disaster area.

        I plan to upgrade asap to 10.8 server.

        For now, I came up with:

        smtpd_client_restrictions = permit_mynetworks permit_sasl_authenticated check_client_access hash:/etc/postfix/whitelist_mtaclientdomains reject_rbl_client zen.spamhaus.org permit
        smtpd_recipient_restrictions = permit_sasl_authenticated permit_mynetworks reject_unauth_destination check_client_access hash:/etc/postfix/whitelist_mtaclientdomains check_policy_service unix:private/policy permit

        Which makes sure some clients are permitted before they end up in either RBL or Policy. Just for you more experienced people: is this OK?

        Does macports overwrite what Apple has provided or does it have its own separate tree (like fink used to have, which means you get another job that is: keeping the second tree up to date)?

        G


        On 2 Feb 2013, at 20:36, James Griffin wrote:

        > --> Gerben Wierda <gerben.wierda@...> [2013-02-02 19:37:41 +0100]:
        >
        >> Actually, I'm still on /usr/libexec/postfix/greylist.pl
        >> as I am using Mac OS X Server 10.6.8 and I haven't dared to upgrade
        >> to a higher version of OS X Server as they were busy crippling it
        >> in many respects.
        >
        > It's actually very easy to upgrade your Postfix installation by
        > compiling the source code. I have needed to do it numerous times,
        > it's worth getting into the habit of upgrading in this way if you're
        > using internet servers.
        >
        > You can also use the Macports system. It will provide a way for you
        > to use the newer Macports Postfix and stop the Apple installed
        > Postfix using launchctl. It's all automated and practically idiot
        > proof.
        >
        >
        > --
        > Primary Key: 4096R/1D31DC38 2011-12-03
        > Key Fingerprint: A4B9 E875 A18C 6E11 F46D B788 BEE6 1251 1D31 DC38
      • Stan Hoeppner
        ... /etc/postfix/main.cf: smtpd_recipient_restrictions = ... reject_unauth_destination - check_client_access pcre:/etc/postfix/client_access
        Message 3 of 13 , Feb 2, 2013
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          On 2/2/2013 11:10 AM, Gerben Wierda wrote:
          > Dag & Dank Wietse,
          >
          > Can I do perl regex, e.g.
          >
          > outmail\d\d\d.snc\d.facebook.com permit
          >
          > or globbing like
          >
          > outmail*.snc4*.facebook.com

          /etc/postfix/main.cf:
          smtpd_recipient_restrictions =
          ...
          reject_unauth_destination
          -> check_client_access pcre:/etc/postfix/client_access
          check_policy_service unix:private/policy

          /etc/postfix/client_access:
          /.*facebook\.com$/ permit
          ...

          You may want to be more specific. I made my example very generic as
          your expression above seems to miss some of their outbound host rdns,
          such as: outappmail004.snc4.facebook.com

          > And secondly, I also get mail I want to leave through where the sender is an operation like messagelabs, but I want to accept only certain senders using messagelabs, e.g. apg.nl or apg-am.nl. So not so much the client but the from, e.g.
          >
          > @... permit
          >
          > how do I do that?

          You can also do this with a PCRE table. If by "from" you mean MAIL
          FROM, then check_sender_access is what you want:

          http://www.postfix.org/postconf.5.html#check_sender_access

          So in the example above, directly after check_client_access, you'd have:

          check_sender_access pcre:/etc/postfix/sender_access

          and a file with expressions something like:

          /etc/postfix/sender_access
          /.*@apg\.nl$/ permit
          ...

          --
          Stan
        • Stan Hoeppner
          ... That s awfully difficult to read. Try putting each on its own line as in the examples we ve given you. Also, put everything under
          Message 4 of 13 , Feb 2, 2013
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            On 2/2/2013 1:55 PM, Gerben Wierda wrote:
            > Just so there is no misunderstanding: I am unhappy running an older version that is not updated with security fixes anymore and I had planned to upgrade before now (but not immediately when 10.8 came out as 10.8.0 Server was not what you say trustworthy. I skipped 10.7 server altogether because it is a disaster area.
            >
            > I plan to upgrade asap to 10.8 server.
            >
            > For now, I came up with:
            >
            > smtpd_client_restrictions = permit_mynetworks permit_sasl_authenticated check_client_access hash:/etc/postfix/whitelist_mtaclientdomains reject_rbl_client zen.spamhaus.org permit
            > smtpd_recipient_restrictions = permit_sasl_authenticated permit_mynetworks reject_unauth_destination check_client_access hash:/etc/postfix/whitelist_mtaclientdomains check_policy_service unix:private/policy permit

            That's awfully difficult to read. Try putting each on its own line as
            in the examples we've given you. Also, put everything under

            smtpd_recipient_restrictions

            and eliminate smtpd_client_restrictions altogether. Now you no longer
            have to duplicate restrictions between them. More importantly, you have
            fine grained control over evaluation order. Thus, this would be much
            better:

            smtpd_recipient_restrictions =
            permit_mynetworks
            permit_sasl_authenticated
            reject_unauth_destination
            check_client_access pcre:/etc/postfix/client_access
            check_sender_access pcre:/etc/postfix/sender_access
            reject_rbl_client zen.spamhaus.org
            check_policy_service unix:private/policy
            ...

            /etc/postfix/client_access:
            /.*facebook\.com$/ permit
            ...

            /etc/postfix/sender_access
            /.*@apg\.nl$/ permit
            ...

            > Which makes sure some clients are permitted before they end up in either RBL or Policy. Just for you more experienced people: is this OK?

            When using separate client and recipient restrictions, as you have
            above, your rbl check against Zen can trigger before your whitelist
            checks, causing a rejection. Using the method I've detailed above
            avoids this situation. Because Postfix performs delayed rejection by
            default, you can put all of your restrictions under
            smtpd_recipient_restrictions and carefully control the order of
            restriction evaluations. I'd guess that every experienced OP on this
            list does it this way. It just doesn't make any sense to do otherwise.

            > Does macports overwrite what Apple has provided or does it have its own separate tree (like fink used to have, which means you get another job that is: keeping the second tree up to date)?

            I have zero experience with MacOS. Sorry.

            --
            Stan
          • Viktor Dukhovni
            ... This is not robust for two reasons, the first is a simple oversight, replace: /.*facebook .com$/ permit with / .facebook .com$/ permit since
            Message 5 of 13 , Feb 2, 2013
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              On Sat, Feb 02, 2013 at 03:34:30PM -0600, Stan Hoeppner wrote:

              > check_client_access pcre:/etc/postfix/client_access
              > ...
              >
              > /etc/postfix/client_access:
              > /.*facebook\.com$/ permit

              This is not robust for two reasons, the first is a simple oversight,
              replace:

              /.*facebook\.com$/ permit

              with

              /\.facebook\.com$/ permit

              since "notfacebook.com" is not "facebook.com" and any SMTP client
              in the real facebook.com domain would be a proper sub-domain.

              The second issue is not easy to fix, transient DNS lookup errors
              (timeouts, ...) may result in a client hostname of "unknown" rather
              than <mumble>.facebook.com. In such cases the whitelist entry will
              not apply. Generally this is a problem as messages may be erroneously
              rejected due to a transient error. In this case, provided the whitelist
              entry is solely to avoid greylisting, this is OK, since greylisting
              is responds with temporary (4XX) error codes.

              --
              Viktor.
            • Stan Hoeppner
              ... It wasn t intended to be robust Viktor, but quite the opposite. ... I guess you missed what came directly after that... ... Sometimes, when a kid asks for
              Message 6 of 13 , Feb 2, 2013
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                On 2/2/2013 3:50 PM, Viktor Dukhovni wrote:
                > On Sat, Feb 02, 2013 at 03:34:30PM -0600, Stan Hoeppner wrote:
                >
                >> check_client_access pcre:/etc/postfix/client_access
                >> ...
                >>
                >> /etc/postfix/client_access:
                >> /.*facebook\.com$/ permit
                >
                > This is not robust for two reasons, the first is a simple oversight,
                > replace:

                It wasn't intended to be robust Viktor, but quite the opposite.

                > /.*facebook\.com$/ permit
                >
                > with
                >
                > /\.facebook\.com$/ permit
                >
                > since "notfacebook.com" is not "facebook.com" and any SMTP client
                > in the real facebook.com domain would be a proper sub-domain.

                I guess you missed what came directly after that...

                On 2/2/2013 3:08 PM, Stan Hoeppner wrote:
                > You may want to be more specific. I made my example very generic as
                > your expression above seems to miss some of their outbound host rdns,
                > such as: outappmail004.snc4.facebook.com

                Sometimes, when a kid asks for an apple, it's better to give him a
                rotten one, so as to teach him to pick his own fresh apples from the
                tree. I.e. I gave him a rotten example of a regex hoping/assuming he'd
                do some legwork and create his own set of fully qualified expressions to
                meet his needs.

                --
                Stan
              • James Griffin
                ... Sure, I can understand that. ... No, Macports does not overwrite what Apple has installed and yes, it does use its own separate filesystem as Fink does;
                Message 7 of 13 , Feb 3, 2013
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                  --> Gerben Wierda <gerben.wierda@...> [2013-02-02 20:55:42 +0100]:

                  > Just so there is no misunderstanding: I am unhappy running an
                  > older version that is not updated with security fixes anymore and
                  > I had planned to upgrade before now (but not immediately when 10.8
                  > came out as 10.8.0 Server was not what you say trustworthy. I skipped
                  > 10.7 server altogether because it is a disaster area. I plan
                  > to upgrade asap to 10.8 server.

                  Sure, I can understand that.

                  > Does macports overwrite what Apple has provided or does it have
                  > ts own separate tree (like fink used to have, which means you get
                  > another job that is: keeping the second tree up to date)?

                  No, Macports does not overwrite what Apple has installed and yes,
                  it does use its own separate filesystem as Fink does; it's under
                  /opt/local. However, they do specify that have programs installed
                  in /usr/local (i.e. manually installed or otherwise) causes issues
                  when using Macports. Totally OT, sorry about that.

                  It does provide you a way of keeping installed programs up-to-date
                  which is why I suggested it. You simply use launctl/Launchd to
                  select which MTA you use; i.e. the Macports installed version or
                  the Apple preinstalled version.
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