Re: Whitelisting Redux

From: Dennis Putnam (no email)
Date: Tue May 01 2007 - 10:49:47 EDT

  • Next message: Peter Rabbitson: "smtp_connection_cache_on_demand"

    On May 1, 2007, at 10:06 AM, Jorey Bump wrote:
    >
    >
    > Then don't do that. :)

    :-)

    >
    > I'm not sure why you're removing permit_sasl_authenticated, but if
    > you don't need it, no harm done.

    I thought that was what you suggested I do.

    >
    > It appears your whitelist is not being consulted. Be sure to issue
    > a 'postfix reload' after editing main.cf.

    I do/did. Why would the white list not be consulted?

    >
    > Okay, looks good.

    Except it doesn't work. :-)

    >
    > Put permit_sasl_authenticated back before permit_mynetworks in
    > smtpd_recipient_restrictions, if you are using authentication for
    > submission via port 25.

    It seems to be working without it but I will. In any case this is not
    effecting the white list is it?

    >
    > This looks fine. Be sure to run 'postmap sender_whitelist' in /etc/
    > postfix, and check your log to be sure there are no associated errors.

    Done.

    >
    > I've duplicated your configuration (easy, since you've nearly
    > duplicated mine), and it works for me (my residential IP is in one
    > of the RBLs, and I can now send from my home computer using the
    > same format you're using). At this point, you'll need to check your
    > logs for clues, but I'll save you some searching:
    >
    > !=

    I missed that detail. I didn't think it used the FROM field since
    that is easily spoofed. The difference is whether the mail originated
    on a Linux box or Windows box. The bad news is that when I add that
    to my white list it still doesn't work.

    >
    > If you want to keep things simple, use this in sender_whitelist:
    >
    > bellsouth.net permit_auth_destination
    >
    > That's safe enough, but it means that anyone can bypass the RBL
    > check by forging the envelope sender address as being from
    > bellsouth.net. Not a big deal, here, but an example why I avoid
    > whitelists for lower maintenance solutions. If you're trying to
    > send mail to your server from a dynamic residential IP *without
    > authentication*, then this is as appropriate a solution as any other.

    I don't really want to open it to all but I might have to try that
    just to see if anything can get through. Will that also work if the
    hostname is home.bellsouth.net? Actually I need to get this working
    not just for this user but for others as well. I want to make sure it
    all works and I understand it before adding more users. These
    otherwise legitimate ISPs that refuse to take responsibility for spam
    originating on their networks drive me nuts. I have things pretty
    tight so we get very little spam leaking through but there are a few
    legitimate sources that don't.

    >
    > Note that you'll have to put your map *after*
    > reject_unauth_destination if you use the bellsouth.net address for
    > outgoing mail (in which case, you should really use their mail
    > server, instead).
    >

    Now I'm confused (as usual). If I send something to
     it will be rejected? Outgoing mail cannot go to
    'bellsouth.net' as that does not resolve to an smtp server. I thought
    postfix looked up the MX record for that address instead.


  • Next message: Peter Rabbitson: "smtp_connection_cache_on_demand"





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