3

I'm trying to migrate our linux system user based post system to virtual users.

I have

  • sendmail with procmail delivery
  • dovecot
  • system users with different uids
  • roundcube web interface

Sendmail handles all mail delivery to user mailboxes, dovecot handles pop3 and imap interraction with users, everything is working like a charm

Now we start to implement active directory globally and i want to refuse from linux system email users prior to ldap virutal users.

I enabled sendmail ldap_routing

define(`confLDAP_DEFAULT_SPEC', `-h "10.1.0.1" -b "ou=portal,dc=univ,dc=priv" -d "cn=portal admin,ou=portal,dc=univ,dc=priv" -MLDAP_AUTH_SIMPLE -P/etc/mail/ldap_pass')dnl

LDAPROUTE_DOMAIN_FILE(`/etc/mail/ldap_route_domains')dnl

FEATURE(`ldap_routing', `null', `ldap -1 -T -v sAMAccountName -k (&(|(objectclass=user)(objectclass=group))(|(mail=%0)(proxyAddresses=smtp:%0)))',`passthru')dnl

created simple alias file for ldap users via perl script. File initially looked like this

sAMAccountName1:    vmail
sAMAccountName2:    vmail
....
sAMAccountNameN:    vmail

enabled dovecot-lda using this howto

Unfortunately sendmail passes real system user name ("vmail" in my case) as -d argument, not sAMAccountName of virtial user with this configuration.

After that i modify my alias file in something like this (inspired by this topic)

sAMAccountName1:    "|/usr/libexec/dovecot/dovecot-lda -d sAMAccountName1"
sAMAccountName2:    "|/usr/libexec/dovecot/dovecot-lda -d sAMAccountName1"
....
sAMAccountNameN:    "|/usr/libexec/dovecot/dovecot-lda -d sAMAccountName1"

This solution fails because of system right problem i can't solve. Here's log messages

Fatal: setgid(5000(vmail) from userdb lookup) failed with euid=8(mail), gid=12(mail), egid=12(mail): Operation not permitted (This binary should probably be called with process group set to 5000(vmail) instead of 12(mail))

dovecot deliver agent defined in sendmail.cf with U=vmail:vmail

Mdovecot,      P=/usr/libexec/dovecot/dovecot-lda,
           F=l59DFMPhnu,
           S=EnvFromL/HdrFromL, R=EnvToL/HdrToL,
           M=51200000,
           U=vmail:vmail,
           T=DNS/RFC822/X-Unix,
           A=/usr/libexec/dovecot/dovecot-lda -d $u

dovecot-lda has same owner and group

-rwxr-x--- 1 vmail vmail 28512 апр.   5  2013 /usr/libexec/dovecot/dovecot-lda

If i use system user mail instead vmail everything starts working fine. But this config seems to me less secure and i want use user vmail with uid > 100 instead of user mail.

So mail delivery fails. I appreciate any help solving this problem.

1
  1. Skip reading if you are not determined :-)

  2. Make vmail special to sendmail (no DNS lookups for destination)

    LOCAL_CONFIG
    CPvmail
    
  3. Use FEATURE(ldap_routing) to select mailHost not mailRoutingAddress

  4. Use FEATURE(mailertable) to select delivery method (mailer)

    mailertable

    vmail  dovecot:dummy
    
  5. Do not make dovecot the local mailer - FEATURE(local_procmail,...)

  6. In dovecot mailer definition use xSMTP rules not xL (local) rules

    http://wiki2.dovecot.org/LDA/Sendmail

  • So step 2 helps to treat it like a host in mailertable. – AnFi Feb 24 '14 at 18:59
  • I have existent local users in same domain. Delivery to local users fails if i use 'bounce' in ldap_routing. And sendmail doesn't return "550 User Unknown" error if recipient doesnt't exists in ldap and in local database if i use 'passthru'. How can i solve this issue? – Ilya 'elcamlost' Rassadin Feb 24 '14 at 19:17
  • And one more issue. I don't store hostMail in Active Directory, is it possible to return some static value from ldap query if mail address was found? – Ilya 'elcamlost' Rassadin Feb 24 '14 at 19:29
  • 1) I suggested redirecting SOME users/addresses to another mailer (dovecot) so standard local mailer would reject mails to non existing users. 2) I can see no easy way but you can use returned "vmail" – AnFi Feb 24 '14 at 20:13
  • 2) i meant syntax. Simple ldap query suggest -v 'some ldap param name' -k 'ldap_filter'. How can i write query, which return simple prefefined string, not value of ldap param specified with -v. – Ilya 'elcamlost' Rassadin Feb 25 '14 at 8:47
1

I was trying to set this up myself and was finding snippets here and there but not a complete recipe. Here's how I did it.

I'm running FreeBSD 10.3-RELEASE, sendmail 8.15.2 and dovecot 2.2.29.

You need a user for the virtual user files:

# passwd
vmail:*:2025:2025:Dovecot Virtual Mail:/var/empty:/usr/sbin/nologin

# group
vmail:*:2025:

The dovecot is simple so let's do that first. Assuming a working dovecot config you will already have at least one userdb setting. Add a new one for virtual users:

# Virtual users
userdb {
        driver = static
        args = uid=vmail gid=vmail home=/var/vmail/%u
}

If you don't have one already add a passdb setting for static credentials:

passdb {
        args = scheme=plain-md5 username_format=%u /usr/local/etc/dovecot/imap-passwd
        driver = passwd-file
}

Create /var/vmail:

mkdir /var/vmail
chown vmail:vmail /var/vmail

and unless you want to manually create directories for each new virtual users, add:

# Virtual users config
lda_mailbox_autocreate = yes

to dovecot.conf (the symptom of not turning on lda_mailbox_autocreate and the directories not existing is EX_TEMPFAIL errors and messages stuck in the local sendmail queue).

Use "doveadm pw -s PLAIN-MD5" and add a line for the new virtual user:

vfred:{PLAIN-MD5}912ec803b2ce49e4a541068d495ab570

Restart dovecot to pick up the new config:

service dovecot restart

Now on to sendmail. If you don't have a mailertable you'll need to add one:

FEATURE(`mailertable')dnl

to sendmail.mc and:

vmail dovecot:dummy

to mailertable. This is telling sendmail to use the dovecot local delivery agent for *@vmail.

At the end of your sendmail.mc you probably have something like:

MAILER(local)dnl
MAILER(smtp)dnl

Append something along the lines of:

dnl
dnl Dovecot virtual user delivery agent
dnl
LOCAL_CONFIG
Mdovecot,
    P=/usr/local/libexec/dovecot/dovecot-lda,
    F=l59DFMPhnu,
    S=EnvFromL/HdrFromL,
    R=EnvToL/HdrToL,
    M=51200000,
    U=vmail:vmail,
    T=DNS/RFC822/X-Unix,
    A=/usr/local/libexec/dovecot/dovecot-lda -d $u

generate a new sendmail.cf and restart sendmail:

service sendmail stop ; sleep 1 ; service sendmail start

("service sendmail restart" is a bit funny under FreeBSD)

Finally add your virtual user to the aliases file:

vfred: vfred@vmail

Run newaliases and test.

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