Postscreen DNSBL Sites

[Charles Marcus]

On 2013-05-14 10:35 AM, Steve Jenkins <[hidden email]> wrote:
>
> # postconf -d | grep smtpd_relay
> smtpd_relay_restrictions = permit_mynetworks, reject_unauth_destination
>
> Any idea why my permit_sasl_authenticated is being ignored in favor of
> the default?

-d gives DEFAULTS

-n is what you want to use to see your changes...

--

Best regards,

Charles

[Bastian Blank-3]

On Tue, May 14, 2013 at 07:35:15AM -0700, Steve Jenkins wrote:
> # postconf -d | grep smtpd_relay
> smtpd_relay_restrictions = permit_mynetworks, reject_unauth_destination
> Any idea why my permit_sasl_authenticated is being ignored in favor of the
> default?

| -d  Print main.cf default parameter settings instead of actual settings.

Bastian

--
Four thousand throats may be cut in one night by a running man.
                -- Klingon Soldier, "Day of the Dove", stardate unknown

[Steve Jenkins-3]

On Tue, May 14, 2013 at 7:38 AM, Charles Marcus <[hidden email]> wrote:

On 2013-05-14 10:35 AM, Steve Jenkins <[hidden email]> wrote:

# postconf -d | grep smtpd_relay
smtpd_relay_restrictions = permit_mynetworks, reject_unauth_destination

Any idea why my permit_sasl_authenticated is being ignored in favor of the default?

-d gives DEFAULTS

-n is what you want to use to see your changes...

Doh. Of course it is. Can you tell I just woke up? :) 

[Steve Jenkins-3]

On Mon, May 13, 2013 at 6:42 PM, Noel Jones <[hidden email]> wrote:

Don't forget that all the other main.cf parameters are still in
effect on your "submission" entry; likely you're seeing unintended
spillover.

I suggest setting ALL the smtpd_*_restrictions entries for
submission in master.cf so you don't have unexpected results.

submission inet n       -       n       -       -       smtpd
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o milter_macro_daemon_name=ORIGINATING
  -o smtpd_client_restrictions=
  -o smtpd_helo_restrictions=
  -o smtpd_sender_restrictions=
  -o smtpd_recipient_restrictions=
  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject

That was the final piece, Noel. Thx. Explicitly setting empty values for those options for submission fixed whatever unintended spillover I was experiencing.

Thanks to everyone's help here, I now have a slightly better understanding of how these restrictions should work, and a much cleaner and easier to understand list of recipient restrictions:

main.cf:

...

# SMTPD Restrictions

smtpd_helo_required = yes

disable_vrfy_command = yes

smtpd_recipient_restrictions =

        reject_invalid_helo_hostname,

        warn_if_reject reject_non_fqdn_helo_hostname,

        reject_unknown_reverse_client_hostname,

        warn_if_reject reject_unknown_helo_hostname,

        check_reverse_client_hostname_access pcre:/etc/postfix/fqrdns.pcre,

        check_helo_access hash:/etc/postfix/helo_access,

        check_sender_access hash:/etc/postfix/sender_access,

        reject_rbl_client zen.spamhaus.org,

        reject_rhsbl_client dbl.spamhaus.org,

        reject_rhsbl_sender dbl.spamhaus.org,

        reject_rhsbl_helo dbl.spamhaus.org,

        permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3],

        permit

smtpd_relay_restrictions =

        permit_mynetworks,

        permit_sasl_authenticated,

        reject_unauth_destination

smtpd_data_restrictions = reject_unauth_pipelining

...

master.cf:

...

submission inet n       -       n       -       -       smtpd

  -o smtpd_tls_security_level=encrypt

  -o smtpd_sasl_auth_enable=yes

  -o milter_macro_daemon_name=ORIGINATING

  -o smtpd_client_restrictions=

  -o smtpd_helo_restrictions=

  -o smtpd_sender_restrictions=

  -o smtpd_recipient_restrictions=

  -o smtpd_relay_restrictions=permit_mynetworks,permit_sasl_authenticated,reject

  -o smtpd_data_restrictions=

  -o smtpd_end_of_data_restrictions=

...

Thanks again!

SteveJ

[/dev/rob0]

On Tue, May 14, 2013 at 07:49:50AM -0700, Steve Jenkins wrote:

> smtpd_recipient_restrictions =
>         reject_invalid_helo_hostname,
>         warn_if_reject reject_non_fqdn_helo_hostname,
>         reject_unknown_reverse_client_hostname,
>         warn_if_reject reject_unknown_helo_hostname,
>         check_reverse_client_hostname_access pcre:/etc/postfix/fqrdns.pcre,
>         check_helo_access hash:/etc/postfix/helo_access,
>         check_sender_access hash:/etc/postfix/sender_access,
>         reject_rbl_client zen.spamhaus.org,
>         reject_rhsbl_client dbl.spamhaus.org,
>         reject_rhsbl_sender dbl.spamhaus.org,
>         reject_rhsbl_helo dbl.spamhaus.org,
>         permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3],
>         permit

The last two lines are no-op. If you have anything you want to be
subjected to the list.dnswl.org whitelist, put it after the
permit_dnswl_client. If not, there is no point in querying it.
--
  http://rob0.nodns4.us/ -- system administration and consulting
  Offlist GMX mail is seen only if "/dev/rob0" is in the Subject:

[Steve Jenkins-3]

On Tue, May 14, 2013 at 8:33 AM, /dev/rob0 <[hidden email]> wrote:

On Tue, May 14, 2013 at 07:49:50AM -0700, Steve Jenkins wrote:
> smtpd_recipient_restrictions =
>         reject_invalid_helo_hostname,
>         warn_if_reject reject_non_fqdn_helo_hostname,
>         reject_unknown_reverse_client_hostname,
>         warn_if_reject reject_unknown_helo_hostname,
>         check_reverse_client_hostname_access pcre:/etc/postfix/fqrdns.pcre,
>         check_helo_access hash:/etc/postfix/helo_access,
>         check_sender_access hash:/etc/postfix/sender_access,
>         reject_rbl_client zen.spamhaus.org,
>         reject_rhsbl_client dbl.spamhaus.org,
>         reject_rhsbl_sender dbl.spamhaus.org,
>         reject_rhsbl_helo dbl.spamhaus.org,
>         permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3],
>         permit

The last two lines are no-op. If you have anything you want to be
subjected to the list.dnswl.org whitelist, put it after the
permit_dnswl_client. If not, there is no point in querying it.

Excellent point. If the next step is going to "permit" anyway, then no use in the extra query. I've moved the dnswl.org line up so that it's just above the three "local" check_* lines.

SteveJ

[Stan Hoeppner]

On 5/14/2013 11:45 AM, Steve Jenkins wrote:

> On Tue, May 14, 2013 at 8:33 AM, /dev/rob0 <[hidden email]> wrote:
>
>> On Tue, May 14, 2013 at 07:49:50AM -0700, Steve Jenkins wrote:
>>> smtpd_recipient_restrictions =
>>>         reject_invalid_helo_hostname,
>>>         warn_if_reject reject_non_fqdn_helo_hostname,
>>>         reject_unknown_reverse_client_hostname,
>>>         warn_if_reject reject_unknown_helo_hostname,
>>>         check_reverse_client_hostname_access
>> pcre:/etc/postfix/fqrdns.pcre,
>>>         check_helo_access hash:/etc/postfix/helo_access,
>>>         check_sender_access hash:/etc/postfix/sender_access,
>>>         reject_rbl_client zen.spamhaus.org,
>>>         reject_rhsbl_client dbl.spamhaus.org,
>>>         reject_rhsbl_sender dbl.spamhaus.org,
>>>         reject_rhsbl_helo dbl.spamhaus.org,
>>>         permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3],
>>>         permit
>>
>> The last two lines are no-op. If you have anything you want to be
>> subjected to the list.dnswl.org whitelist, put it after the
>> permit_dnswl_client. If not, there is no point in querying it.
>
>
> Excellent point. If the next step is going to "permit" anyway, then no use
> in the extra query. I've moved the dnswl.org line up so that it's just
> above the three "local" check_* lines.

"permits" always come before "rejects".  Thus whitelist type entries
should always be at the top of the restrictions list.  As you are using
(client|helo|sender|recipient) sections any whitelisting in
smtpd_recipient_restrictions should typically be at the very top.

permit_dnswl_client list.dnswl.org=127.0.[0..255].[1..3]
                                          ^^^^^^   ^^^^

This shows you are explicitly permitting anything/everything listed in
the dnswl.  Are you sure that is what you want?  I use...

permit_dnswl_client list.dnswl.org=127.0.[2..14].[2..3]

which does not explicitly permit email marketing providers nor any IP
with trustworthiness score of 1.  A score of 1 is equivalent to a
SpamAssassin score of -1, which does not merit a direct shot to the
queue.  That would typically require an SA score of -5.  I want these
clients to go through all of my other restrictions before allowing their
payload into my queue.

Also worth noting, there are currently only 14 categories (3rd octet of
a reply), so specifying 255 is not necessary, and possibly problematic.
 Hypothetically, if dnswl decided one day to create categories 16,
political campaigns, and 17, religious newsletters, you are currently
setup to automatically permit such clients.

Remember, the sole purpose of whitelisting is to bypass all of your
other spam checks and get the mail into your queue unmolested.  IMO, not
every IP listed by dnswl is deserving of this honor, not even close to
all of them.

See section "Return codes" at:  http://www.dnswl.org/tech

--
Stan