Integrate Microsoft Active Directory for user authentication and address book

Attention

Check out the lightweight on-premises email archiving software developed by iRedMail team: Spider Email Archiver.

NOTES:

Summary

With Active Directory (AD) integration, you can get below features:

Since AD uses different LDAP schema, you will lose some iRedMail special features. e.g.

Requirements

To integrate Microsoft Active Directory with iRedMail, you should have:

Install iRedMail

Please follow iRedMail installaion guides to install iRedMail on Linux/BSD with OpenLDAP backend first, we will achieve this AD integration by simply modifying some configure files.

Integrate Microsoft Active Directory with Postfix

We assume:

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.

NOTES:

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

Info

-h is deprecated in new OpenLDAP, please use -H instead. For example, -H ldap://ad.example.com, -H ldap://ad.example.com:389, -H ldaps://ad.example.com:636.

# 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.

If you're using LDAPS, replace -h ad.example.com by -H ldaps://ad.example.com:636 instead:

# ldapsearch -x -H ldaps://ad.example.com:636 -D 'vmail' -W -b 'cn=users,dc=example,dc=com'
Enter password: password_of_vmail

If LDAPS doesn't work, you may need to update parameter TLS_CACERT in /etc/openldap/ldap.conf (RHEL/CentOS) or /etc/ldap/ldap.conf to use correct CA certificate. For example:

TLS_CACERT /etc/pki/tls/certs/ca-bundle.trust.crt

TLS_CACERT /etc/ssl/certs/ca-certificates.crt

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=''
postconf -e sender_dependent_relayhost_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.

postconf -e smtpd_sender_login_maps='proxy:ldap:/etc/postfix/ad_sender_login_maps.cf'

postconf -e virtual_mailbox_maps='proxy:ldap:/etc/postfix/ad_virtual_mailbox_maps.cf'

postconf -e virtual_alias_maps='proxy:ldap:/etc/postfix/ad_virtual_group_maps.cf'

example.com dovecot

Note: the name 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

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

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: We hard-code user's mailbox path in result_format = parameter, it will be something like example.com/username/Maildir/.

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

Notes:

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

Remove iRedAPD integration in Postfix

iRedAPD relies on iRedMail LDAP scheme, so it's useless if you integrate iRedMail with Active Directory. We should remove the integration in Postfix to save some system resource.

To disable iRedAPD, please read tutorial: Manage iRedAPD.

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:

Attention

If you use LDAPS and hosts = doesn't work, please replace it by uris = instead. Check Dovecot tutorial for more details.

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

# Below two are required by command 'doveadm mailbox ...'
iterate_attrs   = userPrincipalName=user
iterate_filter  = (&(userPrincipalName=*)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))

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      = mail=master_user,mail=user,=home=/var/vmail/vmail1/%Ld/%Ln/,=mail=maildir:~/Maildir/

Restart dovecot service to make it work.

Attention

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
}

You can also modify the user_attrs = line to get per-user quota from a LDAP attribute in AD. For example, query per-user quota limit from attribute postOfficeBox which contain an integer number and treated as number of gigabytes:

user_attrs      = =home=/var/vmail/vmail1/%Ld/%Ln/,=mail=maildir:~/Maildir/,postOfficeBox=quota_rule=*:storage=%{ldap:postOfficeBox}G

Note: This per-user quota will override the one hard-coded in dovecot.conf.

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:

#
# "sql" is personal address book stored in roundcube database.
# "global_ldap_abook" is the new LDAP address book for AD, we will create it below.
#
$config['autocomplete_addressbooks'] = array("sql", "global_ldap_abook");

# Enable setting below if Roundcube returns 'user@127.0.0.1' as email address
#$config['mail_domain'] = '%d';

#
# Global LDAP Address Book with AD.
#
$config['ldap_public']["global_ldap_abook"] = array(
    'name'          => 'Global 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',
        'displayname'   => 'displayName',
        'surname'       => 'sn',
        'firstname'     => 'givenName',
        'jobtitle'      => 'title',
        'department'    => 'department',
        'company'       => 'company',
        'email'         => 'mail:*',
        'phone:work'    => 'telephoneNumber',
        'phone:home'    => 'homePhone',
        'phone:mobile'  => 'mobile',
        'phone:workfax' => 'facsimileTelephoneNumber',
        'phone:pager'   => 'pager',
        'phone:other'   => 'ipPhone',
        'street:work'   => 'streetAddress',
        'zipcode:work'  => 'postalCode',
        'locality:work' => 'l',
        'region:work'   => 'st',
        'country:work'  => 'c',
        'notes'         => 'description',
        'photo'         => 'jpegPhoto',   // Might be 'thumbnailPhoto' for
                                          // compatibility with some other
                                          // Microsoft software
        'website'       => 'wWWHomePage',
    ),
    'sort'          => 'cn',
    'scope'         => 'sub',
    'filter'        => "(&(|(objectclass=person)(objectclass=group))(!(userAccountControl:1.2.840.113556.1.4.803:=2)))",
    '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
);

Enable Active Directory integration in SOGo Groupware

Edit SOGo config file /etc/sogo/sogo.conf, comment out the LDAP address book setting added by iRedMail, and add new setting for AD like below:

    SOGoUserSources = (
        {
            // Used for user authentication
            type = ldap;
            id = users;
            canAuthenticate = YES;
            isAddressBook = NO;
            displayName = "LDAP Authentication";

            hostname = "ldap://ad.example.com:389";   // <- Set to ldaps://ad.example.com:636 for LDAPS.
            baseDN = "cn=users,dc=example,dc=com";
            bindDN = "vmail";
            bindPassword = "password_of_vmail";
            filter = "objectClass=person AND userPrincipalName='*' AND (NOT userAccountControl:1.2.840.113556.1.4.803:=2)";
            scope = SUB;

            // always keep binding to the LDAP server using the DN of the
            // currently authenticated user. bindDN and bindPassword are still
            // required to find DN of the user.
            // Note: with default LDAP acl configured by iRedMail, user doesn't
            //       have privilege to query o=domains,dc=delmsgs,dc=freeddns,dc=org.
            //       so this doesn't work.
            bindAsCurrentUser = YES;

            // The algorithm used for password encryption when changing
            // passwords without Password Policies enabled.
            // Possible values are: plain, crypt, md5-crypt, ssha, ssha512.
            userPasswordAlgorithm = ssha512;

            CNFieldName = cn;
            IDFieldName = userPrincipalName;
            // value of UIDFieldName must be unique on entire server
            UIDFieldName = userPrincipalName;
            IMAPLoginFieldName = userPrincipalName;
            MailFieldNames = (userPrincipalName);
            bindFields = (userPrincipalName);
        },
        {
            // Used for global address book
            type = ldap;
            id = global_addressbook;
            canAuthenticate = NO;
            isAddressBook = YES;
            displayName = "Global Address Book";
            bindAsCurrentUser = YES;

            // Listing of this LDAP source is only possible when performing a
            // search (respecting the SOGoSearchMinimumWordLength parameter)
            // or when explicitely typing a single dot.
            // Defaults to YES when unset.
            //
            // WARNING: if you have many accounts in this address book, it may
            //          reach server-side query size limit, or cause
            //          performance issue.
            listRequiresDot = NO;

           // Set to ldaps://ad.example.com:636 for LDAPS.
            hostname = "ldap://ad.example.com:389";
            baseDN = "cn=users,dc=example,dc=com";
            bindDN = "vmail";
            bindPassword = "password_of_vmail";
            filter = "(objectClass=person OR (objectClass=group AND mail='*')) AND (NOT userAccountControl:1.2.840.113556.1.4.803:=2)";
            scope = SUB;

            IDFieldName = userPrincipalName;
            bindFields = (userPrincipalName);
            // value of UID field must be unique on whole server.
            UIDFieldName = userPrincipalName;
            IMAPLoginFieldName = userPrincipalName;

            CNFieldName = cn;
            SearchFieldNames = (mail, cn, sAMAccountName, displayName, sn, givenName);

            mapping = {
              ou = ("department", "ou");
              street = ("streetAddress", "street");
              mozillaworkurl = ("wWWHomePage", "mozillaworkurl");
              description = ("info", "description");
            };
        }
    );

Additions documents

All documents are available in GitHub repository, and published under Creative Commons license. You can download the latest version for offline reading. If you found something wrong, please do contact us to fix it.