Mail system

Mail delivery configuration with LDAP

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Last time I wrote about users’ authentication in LDAP directory to allow them receiving and sending e-mails. Now is time to configure Postfix for mail delivery to appropriate mailboxes.
If you compile Postfix themselves, you need to remember to add support for LDAP. My description is based on Ubuntu, so I only need to install postfix-ldap package:

$ sudo -i
# apt-get install postfix-ldap

This will add support for ldap: maps in Postfix.

Now we go to Postfix configuration:

# cd /etc/postfix
# vi main.cf

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Mail system authentication in LDAP

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I suppose that Dovecot and Postfix are up and running, and you can receive and send mail with system user (see previous posts). It is time to configure authentication in LDAP.

Use of directory service to user authentication allows for flexible management of mail system, hosting and so on. LDAP is established standard for authentication and authorization and almost all software which requires authentication support this protocol.

Let’s begin from POP3/IMAP Dovecot server, which also deliver authentication mechanism for Postfix:


/usr/bin/sudo -i
cd /etc/dovecot
vi dovecot-ldap.conf

In this file you need to define LDAP server/s parameters, authentication method, filter and attributes. I list those most important:


hosts = localhost
auth_bind = yes
base = o=hosting,dc=example,dc=com
scope = subtree
user_attrs = homeDirectory=home
user_filter = (&(objectClass=mailUser)(mail=%u))
pass_attrs = mail=user,userPassword=password
pass_filter = (&(objectClass=mailUser)(mail=%u))

Installation of mail system on Ubuntu

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I assume that you have installed system with basic configuration and SSH running. After login to system we can install dovecot-postfix package, which is described as fully functional mail server:

drfugazi@charr:~% sudo aptitude install dovecot-postfix
[sudo] password for drfugazi:
Reading extended state information
Initializing package states... Gotowe
The following NEW packages will be installed:
  dovecot-common{a} dovecot-imapd{a} dovecot-pop3d{a} dovecot-postfix
0 packages upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
Need to get 7957kB of archives. After unpacking 15,1MB will be used.
Do you want to continue? [Y/n/?] y
...
Configuring dovecot-common (1:1.2.9-1ubuntu6.1) ...
Creating config file /etc/dovecot/dovecot.conf with new version
Creating config file /etc/dovecot/dovecot-ldap.conf with new version
Creating config file /etc/dovecot/dovecot-sql.conf with new version

Now we should check if Dovecot is running and we can connect to IMAP server on localhost:

Installation and configuration of OpenLDAP

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Installation and basic configuration of LDAP directory service (OpenLDAP) on Ubuntu:

sudo aptitude install slapd ldap-utils

This description is based on HowtoForge document for Karmic Koala. I used to be to configure of OpenLDAP in slapd.conf file, but this is old method. Here we have possibility to modify LDAP configuration without restart of LDAP server.

cd /etc/ldap

At first I suggest you to add some schemas, which contains objectclasses and attributes useful later:

ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/ldap/schema/cosine.ldif
ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/ldap/schema/inetorgperson.ldif
ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/ldap/schema/nis.ldif

If you have problem with addition of above because of insufficient permissions then switch to root with sudo su - or sudo -i