We have been using eDirectory for quite a while on Linux now and the time has come that a client would like to use eDirectory to authenticate other Linux services through LDAP to eDirectory. We have been tasked to integrate the authentication of Postfix, Dovecot, Squid, and SquirrelMail via LDAP to Novell’s eDirectory.
The approach that we have decided to use for Postfix was to do virtual email hosting, while letting Postfix pull user accounts from LDAP, and store the emails on virtual mailboxes in the Linux machine. Dovecot will also do a password lookup, while using a global user account on Linux that will have exclusive access to the “home” directory of virtual email users. Squid will do direct LDAP access via the squid_ldap_auth helper. SquirrelMail on the other hand will just pull off authentication via Dovecot.
I will only be providing the steps on how to authenticate Postfix and Dovecot to eDirectory via LDAP. In order to perform the following outlined steps, it will be helpful to already have Novell eDirectory/NDS running on one server. It must listen on either port 389 or 636 by default. However, if you’ve modified the ports, make sure you take note of them for later use. Also on the eDirectory/NDS, we will need to have one user that will act as a proxy user for LDAP lookups. Though this can also be achieved by assigning [Public] as a Trustee with “browse” rights to the root of your tree (eg. “o=your-context” ). How to install eDirectory on Linux is beyond the scope of this article. Feel free to visit the Novell Documentation.
We have used SuSE Linux Enterprise Server 10 SP 1 to perform all of the steps. It doesn’t matter though which Linux distribution you’ll be using or if you’ll be accessing NDS on Netware, as long as the backend LDAP server will be eDirectory/NDS.
POSTFIX CONFIGURATION
A. main.cf
Postfix already comes with SLES10 SP1 built-in. It only requires a little tweaking to allow it to authenticate to eDirectory via LDAP. We will then throw in virtual email hosting configuration for good measure.
If you need to compile Postfix, configure and compile it as standard. However in the main.cf, we will be adding a couple of parameters to make Postfix work with LDAP. The following parameters are what we need. The rest not included here are standard Postfix configs, including restrictions and UCEs.
inet_protocols = all
inet_interfaces = all
biff = no
mail_spool_directory = /var/spool/mail
myhostname = your-server-hostname
mydomain = put-a-dummy-domain-here.
mydestination = localhost.$mydomain,localhost,$mydomain,$myhostname
mynetworks = 192.168.100.0/24 127.0.0.1
mynetworks_style = subnet
Modify
myhostname and
mynetworks to reflect your own settings. Put a dummy domain name in
mydomain. We will put our real domain in the
virtual_mailbox_domains parameter.
local_recipient_maps = ldap:/etc/postfix/ldap-user-auth.cf
local_transport = virtual
virtual_mailbox_domains = your-real-domain-here
virtual_mailbox_base = /var/spool/vmail
virtual_mailbox_maps = hash:/etc/postfix/virtual_mailboxes
virtual_minimum_uid = 106
virtual_uid_maps = static:106
virtual_gid_maps = static:12
local_recipient_maps will point to our LDAP authentication routines contained in
ldap-user-auth.cf.
virtual_mailbox_domains will have our real domain since we will be using virtual email users that will be pulled off from eDirectory via LDAP later.
virtual_mailbox_maps will point to our hash file which is actually a mapping of email addresses to their associated virtual mail boxes relative to the default directory assigned in
virtual_mailbox_base.
virtual_uid_maps and virtual_gid_maps will point to the only mail-related user in the entire SLES10 system — the global user which will be used by Postfix and Dovecot to drop emails to the mailboxes of our virtual email users. The global user, in our case is called “vmail” as assigned a uid of 106 and a gid of 12 (mail). It was created using the terminal by typing the following as root:
useradd -u 106 -g 12 -d /var/spool/vmail -s /bin/bash vmail
You will also need to create /var/spool/vmail and change ownership (chown) to vmail:mail.
smtpd_sasl_auth_enable = yes
smtpd_sasl_exceptions_networks = $mynetworks
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
Enable SASL authentication by setting
smtpd_sasl_auth_enable = yes. We will be using Dovecot SASL therefore, we will need to set
smtpd_sasl_type = dovecot and
smtpd_sasl_path = private/auth.
B. ldap-user-auth.cf
Here are the things we need to put for LDAP authentication for Postfix.
server_host = your-LDAP-server-ip
search_base = o=context
version = 3
query_filter = (&(objectClass=Person)(uid=%s))
result_attribute = uid
bind = yes
bind_dn = cn=ProxyLDAPUser.o=context
scope = sub
C. virtual_mailboxes
Since Postfix will be looking for “real” users, we will need to map email addresses to actual directory locations for each user using the virtual_mailboxes mapping. Arguments for the mapping will take the form of:
email address username/Maildir
Example:
user1@mydummydomain.com user1/Maildir
user2@mydummydomain.com user2/Maildir
:
Save the file, and generate the Postfix database by running
postmap virtual_mailboxes in the terminal.
DOVECOT CONFIGURATION (pertinent only)
A. dovecot.conf
Dovecot can be compiled off the bat using ./configure, and then following it with make and make install respectively. However, since we will be letting Dovecot authenticate through LDAP, we will need to compile it with LDAP support therefore do this by typing ./configure --with-ldap and proceed as usual.
Here are the pertinent parameters that we will need to declare in dovecot.conf to enable it to work with LDAP. The rest of the configs (not shown) are standard Dovecot config.
mail_location = maildir:/var/spool/vmail/%u/Maildir
first_valid_uid = 106
last_valid_uid = 106
auth_username_format = %Lu
auth default {
mechanisms = plain login
passdb ldap {
args = /etc/dovecot/dovecot-ldap_passdb.conf
}
userdb static {
args = uid=106 gid=12 home=/var/spool/vmail/%u
}
socket listen {
master {
path = /var/run/dovecot/auth-master
mode = 0660
user = vmail
group = mail
}
client {
path = /var/spool/postfix/private/auth
mode = 0660
user = postfix
group = mail
}
}
}
B. dovecot-ldap_passdb.conf
hosts = LDAP-server-ip
base = o=context
ldap_version = 3
scope = subtree
#for LDAP Bind
auth_bind = yes
pass_filter = (&(objectClass=Person)(uid=%u))
Replace
LDAP-server-ip with the server ip of the eDirectory server. Replace
o=context with your eDirectory context.
VALIDATING
Run Postfix by typing rcpostfix start and run Dovecot by typing /usr/local/sbin/dovecot. You will then be able to try and connect via telnet on port 25, 143 and/or 110 to test Postfix and Dovecot. You can test Dovecot if the user can authenticate by going:
telnet server-ip 143
You will then receive the server header/reply. You can proceed to initiate authentication by going:
1 login user password
If you’ll receive an
OK message, congratulations!
You can monitor Postfix by looking at /var/log/mail using the command tail -f /var/log/mail.
Feel free to post your questions and comments. Good Luck!
technorati tags: Postfix, Dovecot, eDirectory, LDAP, authentication, Linux, Novell, SLES10, Netware
linux, nagios, nrpe, monitoring
