Integrate Microsoft Active Directory in iRedMail


We assume:

  • Hostname of your AD server is ad.example.com, listen on port 389. And it’s accessible from iRedMail server.
    • We will use this hostname below, you can replace it by IP address of this AD server if you want.
    • If you want to force LDAP connection with LDAPS, use port 636 instead.
  • Base dn in AD is dc=example,dc=com, email addresses of all users end with @example.com (Your mail domain is example.com).
  • All user accounts and mail list accounts are placed under dn cn=Users,dc=example,dc=com. Note: LDAP dn is case-insensitive.
  • For ldap connection, protocol version 3 is recommended.
  • Store all mails on Linux/BSD servers, not on AD server.
    • Storage directory is /var/vmail/vmail1, same as default in iRedMail.
    • Mailbox of user support@example.com will be /var/vmail/vmail1/example.com/support/Maildir/ (Maildir format).

Create user account in AD, used for LDAP query

With iRedMail (OpenLDAP backend), we have a low-privileged account cn=vmail,dc=xxx,dc=xxx with read-only privilege. And we suggest you create a same account vmail in AD, with strong and complex password.

Please make sure this newly created user is able to connect to AD server with below command on iRedMail server:

# ldapsearch -x -h ad.example.com -D 'vmail' -W -b 'cn=users,dc=example,dc=com'
Enter password: password_of_vmail

If it prints all users stored in AD server, then it’s working as expected.

Enable LDAP query with AD in Postfix

Disable unused iRedMail special settings:

# postconf -e virtual_alias_maps=''
# postconf -e sender_bcc_maps=''
# postconf -e recipient_bcc_maps=''
# postconf -e relay_domains=''
# postconf -e relay_recipient_maps=''

Add your mail domain name in smtpd_sasl_local_domain and virtual_mailbox_domains:

# postconf -e smtpd_sasl_local_domain='example.com'
# postconf -e virtual_mailbox_domains='example.com'

Change transport maps setting:

# postconf -e transport_maps='hash:/etc/postfix/transport'

Enable AD query. Note: We will create these 3 files later.

  • Verify SMTP senders
# postconf -e smtpd_sender_login_maps='proxy:ldap:/etc/postfix/ad_sender_login_maps.cf'
  • Verify local mail users
# postconf -e virtual_mailbox_maps='proxy:ldap:/etc/postfix/ad_virtual_mailbox_maps.cf'
  • Verify local mail lists/groups.
# postconf -e virtual_alias_maps='proxy:ldap:/etc/postfix/ad_virtual_group_maps.cf'
  • Create/edit file: /etc/postfix/transport.
example.com dovecot

Note: dovecot used here is a Postfix transport defined in /etc/postfix/master.cf, used to deliver received emails to local user mailboxes.

Run postmap so that postfix can read it:

# postmap hash:/etc/postfix/transport
  • Create file: /etc/postfix/ad_sender_login_maps.cf:
server_host     = ad.example.com
server_port     = 389
version         = 3
bind            = yes
start_tls       = no
bind_dn         = vmail
bind_pw         = password_of_vmail
search_base     = cn=users,dc=example,dc=com
scope           = sub
query_filter    = (&(userPrincipalName=%s)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
result_attribute= userPrincipalName
debuglevel      = 0
  • Create file: /etc/postfix/ad_virtual_mailbox_maps.cf:
server_host     = ad.example.com
server_port     = 389
version         = 3
bind            = yes
start_tls       = no
bind_dn         = vmail
bind_pw         = passwd_of_vmail
search_base     = cn=users,dc=example,dc=com
scope           = sub
query_filter    = (&(objectclass=person)(userPrincipalName=%s))
result_attribute= userPrincipalName
result_format   = %d/%u/Maildir/
debuglevel      = 0

Note: Here, we hard-code user’s mailbox path in [domain]/[username]/Maildir/ format (result_format parameter). for example: example.com/postmaster/Maildir/.

  • Create file: /etc/postfix/ad_virtual_group_maps.cf:
server_host     = ad.example.com
server_port     = 389
version         = 3
bind            = yes
start_tls       = no
bind_dn         = vmail
bind_pw         = password_of_vmail
search_base     = cn=users,dc=example,dc=com
scope           = sub
query_filter    = (&(objectClass=group)(mail=%s))
special_result_attribute = member
leaf_result_attribute = mail
result_attribute= userPrincipalName
debuglevel      = 0

Note:

  • If your user have email address in both mail and userPrincipalName, you will get duplicate result. Comment out leaf_result_attribute line will fix it.
  • If your mail group account doesn’t contain attribute mail and userPrincipalName, please try query_filter = (&(objectClass=group)(sAMAccountName=%u)) instead.

Also, we need to remove iRedAPD related settings in Postfix:

  1. Open Postfix config file /etc/postfix/main.cf
  2. Remove setting check_policy_service inet:127.0.0.1:7777.

Verify LDAP query with AD in Postfix

We can now use command line tool postmap to verify AD integration in postfix. Before testing, we have to create two testing mail accounts first:

  1. Create a mail user in AD. e.g. user@example.com.
  2. Create a mail group in AD. e.g. testgroup@example.com, then assign mail user user@example.com as group member.
  3. Query mail user account with below command:
# postmap -q user@example.com ldap:/etc/postfix/ad_virtual_mailbox_maps.cf
example.com/user/Maildir/

If nothing returned by the command, it means LDAP query doesn’t get expected result. Please set debuglevel = 1 file /etc/postfix/ad_virtual_mailbox_maps.cf, then query again, it now will print detailed debug message. If you’re not familiar with LDAP related info, please post the debug message in our online support forum to get help.

Verify sender login check:

# postmap -q user@example.com ldap:/etc/postfix/ad_sender_login_maps.cf
user@example.com

Verify mail group

# postmap -q testgroup@example.com ldap:/etc/postfix/ad_virtual_group_maps.cf
user@example.com

NOTE: postmap return nothing if:

  1. mail group doesn’t exist
  2. mail group doesn’t have any members

Enable Active Directory integration in Dovecot

To query AD instead of local LDAP server, we have to modify Dovecot config file /etc/dovecot/dovecot-ldap.conf like below:

hosts           = ad.example.com:389
ldap_version    = 3
auth_bind       = yes
dn              = vmail
dnpass          = passwd_of_vmail
base            = cn=users,dc=example,dc=com
scope           = subtree
deref           = never
user_filter     = (&(userPrincipalName=%u)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
pass_filter     = (&(userPrincipalName=%u)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
pass_attrs      = userPassword=password
default_pass_scheme = CRYPT
user_attrs      = =home=/var/vmail/vmail1/%Ld/%Ln/Maildir/,=mail=maildir:/var/vmail/vmail1/%Ld/%Ln/Maildir/

Restart dovecot service to make it work.

Note: we don’t have per-user quota limit here, you can set a hard-coded quota for all users in /etc/dovecot/dovecot.conf. For example:

plugin {
    [... omit other settings here ...]

    # Format: integer number + M/G/T (M -> MB, G -> GB, T -> TB).
    quota_rule = *:storage=1G
}

Now use command telnet to verify AD query after restarted Dovecot service:

# telnet localhost 143                     # <- Type this
* OK [...] Dovecot ready.

. login user@example.com password_of_user  # <- Type this. Do not miss the dot in the beginning
. OK [...] Logged in

^]                                         # <- Quit telnet with "Ctrl+]", then type 'quit'.

Note: Do NOT miss the dot character before login command. if it returns Logged in, then dovecot + AD works.

Enable Active Directory integration in Roundcube webmail for Global LDAP Address Book

Edit roundcube config file config/config.inc.php, comment out the LDAP address book setting added by iRedMail, and add new setting for AD like below:

  • on RHEL/CentOS and OpenBSD: it’s /var/www/roundcubemail/config/config.inc.php
  • on Debian/Ubuntu: it’s /usr/share/apache2/roundcubemail/config/config.inc.php
  • on FreeBSD: it’s /usr/local/www/roundcubemail/config/config.inc.php
#
# "sql" is personal address book stored in roundcube database.
# "example.com" is new LDAP address book with AD, we will create it below.
#
$config['autocomplete_addressbooks'] = array("sql", "example.com");

#
# Global LDAP Address Book with AD.
#
$config['ldap_public']["global_ldap_abook"] = array(
    'name'          => 'Global LDAP Address Book',
    'hosts'         => array("ad.example.com"),      // <- Set AD hostname or IP address here.
    'port'          => 389,
    'use_tls'       => false,   // <- Set to true if you want to use LDAP over TLS.
    'ldap_version'  => '3',
    'network_timeout' => 10,
    'user_specific' => false,

    'base_dn'       => "cn=users,dc=example,dc=com", // <- Set base dn in AD
    'bind_dn'       => "vmail",                      // <- bind dn
    'bind_pass'     => "password_of_vmail",          // <- bind password
    'writable'      => false,                        // <- Do not allow mail user write data back to AD.

    'search_fields' => array('mail', 'cn', 'sAMAccountName', 'displayname', 'sn', 'givenName'),

    // mapping of contact fields to directory attributes
    'fieldmap' => array(
        'name'        => 'cn',
        'surname'     => 'sn',
        'firstname'   => 'givenName',
        'title'       => 'title',
        'email'       => 'mail:*',
        'phone:work'  => 'telephoneNumber',
        'phone:mobile' => 'mobile',
        'street'      => 'street',
        'zipcode'     => 'postalCode',
        'locality'    => 'l',
        'department'  => 'departmentNumber',
        'notes'       => 'description',
        'name'        => 'cn',
        'surname'     => 'sn',
        'firstname'   => 'givenName',
        'title'       => 'title',
        'email'       => 'mail:*',
        'phone:work'  => 'telephoneNumber',
        'phone:mobile' => 'mobile',
        'phone:workfax' => 'facsimileTelephoneNumber',
        'street'      => 'street',
        'zipcode'     => 'postalCode',
        'locality'    => 'l',
        'department'  => 'departmentNumber',
        'notes'       => 'description',
        'photo'       => 'jpegPhoto',
    ),
    'sort'          => 'cn',
    'scope'         => 'sub',
    //'filter'        => "(&(objectclass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))",
    'filter'        => "(mail=*@*)",
    'fuzzy_search'  => true,
    'vlv'           => false,   // Enable Virtual List View to more efficiently fetch paginated data (if server supports it)
    'sizelimit'     => '0',     // Enables you to limit the count of entries fetched. Setting this to 0 means no limit.
    'timelimit'     => '0',     // Sets the number of seconds how long is spend on the search. Setting this to 0 means no limit.
    'referrals'     => false,  // Sets the LDAP_OPT_REFERRALS option. Mostly used in multi-domain Active Directory setups
);