Dovecot Submission Proxy Auth

[Paul Hecker]

Hi,

> On 6. Apr 2018, at 18:58, Odhiambo Washington <odhiambo at gmail.com> wrote:
> 
> Hi Paul,
> 
> Care to share your config (even OFFLIST) that has successfully integrated Dovecot Submission service with Exim??

here the steps I have done to integrate Dovecot submission in Exim:

- Create and set the acl_smtp_mailauth ACL:

acl_smtp_mailauth = acl_check_mailauth

acl_check_mailauth:
  accept
    hosts          = <; 127.0.0.1 ; ::1
    condition      = ${if eq{$interface_port}{10025}}
    log_message    = Will accept MAIL AUTH parameter for $authenticated_sender
    
  deny


- add a deny fo all connections to 10025 without MAIL AUTH parameter in acl_smtp_mail ACL:

  deny
    condition      = ${if eq{$interface_port}{10025}}
    condition      = ${if eq{$authenticated_sender}{}}
    message        = All connections on port $interface_port need MAIL AUTH sender

- in Dovecot, add the following submission parameters

submission_relay_port = 10025
submission_relay_ssl = starttls
submission_relay_ssl_verify = no

All the remaining parts of the Dovecot config is the default for submission protocol/service, copied either from the sources (default config) or from here:

https://wiki.dovecot.org/Submission

Feel free is you have any further questions.

Regards,
Paul


> 
> I use Exim+Dovecot (Exim4U) and wouldn't mind exploring this.
> 
> Thanks in advance.
> 
> 
> On 6 April 2018 at 19:15, Paul Hecker <paul at iwascoding.com> wrote:
> Hi,
> 
> Thanks you very much. This did the trick!
> 
> > On 6. Apr 2018, at 15:56, Stephan Bosch <stephan at rename-it.nl> wrote:
> >
> >
> >
> > Op 6-4-2018 om 13:52 schreef Paul Hecker:
> >> Hi,
> >>
> >> Dovecot 2.3.1 (8e2f634). Could not get Dovecot to forward the (plain) authentication to the SMTP server using submission. Reason why I need it is sender spoofing (do not want my employees to send messages in behalf of me).
> >>
> >> In exim I can disable sender spoofing with the authenticated user. When sending through dovecot, exim either does not accept the email (need auth) or relay every sender address (because relaying from localhost).
> >>
> >> Am I missing a setting or do I need any additional field in the (MySQL) user_query/password_query to forward the password?
> >>
> >> You can find my config here:
> >>
> >> https://gist.github.com/lluuaapp/7daddf761131da47237b0f45e6bab5a8
> >
> > That would be possible using the following SMTP AUTH feature:
> >
> > https://tools.ietf.org/html/rfc4954#section-5
> >
> > Which is apparently supported by Exim: https://www.exim.org/exim-html-current/doc/html/spec_html/ch-smtp_authentication.html#SECTauthparamail
> > This requires explicit configuration, so it will not work out of the box.
> 
> Here is what I did:
> 
> I had to add the acl_smtp_mailauth to only allow this on a certain port. Then I had to duplicate my code for sender spoofing for authenticated users and change the $authenticated_id -> $authenticated_sender.
> 
> Besides that, I must use TLS (in my case STARTTLS) so that Dovecot actually sends the MAIL AUTH parameter.
> 
> >
> > The Dovecot Submission service should support this too. It sends an AUTH parameter with the MAIL command (currently only then the username is a valid SMTP address). However, I must say, I haven't tested this recently.
> 
> I can confirm that it works (only with TLS with my current configuration, see above).
> 
> >
> > I can try this in a few days. Feel free to experiment with this yourself.
> >
> > Regards,
> >
> > Stephan.
> 
> Thanks again,
> Paul
> 
> 
> 
> 
> -- 
> Best regards,
> Odhiambo WASHINGTON,
> Nairobi,KE
> +254 7 3200 0004/+254 7 2274 3223
> "Oh, the cruft."

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