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Re: Block certain remote hosts on submission port

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  • Noel Jones
    ... If you do the reject in postfix you ll be able to see the sender details, which may be valuable for seeing which accounts have been compromised and/or
    Message 1 of 11 , Aug 24, 2013
      On 8/24/2013 3:52 PM, Stan Hoeppner wrote:
      > On 8/24/2013 1:18 PM, LuKreme wrote:
      >>
      >> On 22 Aug 2013, at 21:28 , Stan Hoeppner <stan@...> wrote:
      >>
      >>> ~$ wget http://ipdeny.com/ipblocks/data/countries/us.zone
      >>> ~$ sed 's/$/ OK/g' us.zone > us.cidr
      >>> ~$ cp us.cidr /etc/postfix
      >>> ~$ postfix reload
      >>>
      >>> and you're off to the races.
      >>
      ...
      >
      > And BTW, it's better to do this at the firewall if at all practical.

      If you do the reject in postfix you'll be able to see the sender
      details, which may be valuable for seeing which accounts have been
      compromised and/or troubleshooting false positive reports.

      All the firewall can show is some IP was blocked.

      >
      >> 2) If I did this I also would like to log these rejections to a separate file, possible?
      >
      > Not directly. You'd specify a custom reject code then parse your mail
      > log for that, pipe to another file. If you do it at the firewall it
      > would depend on the firewall's features.

      You can append a wildcard reject AT THE END of the cidr file with a
      custom message. That message will be sent to the client and will be
      included in your log.

      # us cidr table
      ... everything else
      0.0.0.0/0 REJECT submission not allowed from your location geoip


      >
      >> Under 2.10, would it make sense to put those restriction in the smtpd_relay_restrictions if port 25 is open for connections?
      >
      > In the other half of the instructions I gave, which you cut, I show that
      > this needs to be done in master.cf. smtpd_foo_restrictions in main.cf
      > are global. You want this restriction only on the submission port, not
      > the public smtp port.
      >


      Yes indeed.



      -- Noel Jones
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