OpenLDAP Everywhere Revisited

To begin configuring the Linux LDAP client, you need to install the name switch service package, nss_ldap. The Red Hat tool /usr/bin/authconfig is handy for configuring the client. Select Use LDAP and fill in the fields so that they read Server: ldapserver.foo.com and Base DN: dc=foo,dc=com. Authconfig writes to these files: /etc/ldap.conf, /etc/openldap/ldap.conf and /etc/nsswitch.conf.

Verify that /etc/nsswitch.conf has the following entries:

passwd:     files ldap
shadow:     files ldap
group:      files ldap
automount:  files ldap

Verify that /etc/ldap.conf has these entries:

host ldapserver.foo.com
base dc=foo,dc=com

Verify that /etc/openldap/ldap.conf has these entries:

HOST ldapserver.foo.com
BASE dc=foo,dc=com

The user's password and group entries must be removed from the password and group files on the NFS server where home directories live. Create backups and then edit /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow to remove the LDAP real people entries. In our case, /etc/passwd should have no accounts left with a UID from 1000 to 9999.

To test, log in to a Linux LDAP client using an LDAP user name. You should see the appropriate login shell and home directory for the user. To test auto.misc shares, you must access the share by name, for example:

cd /share/redhat

Automount only mounts NFS shares as they are used, so the directory /share/redhat is not visible until it has been accessed.

The main purpose of using Samba and LDAP together is to achieve unified login for Microsoft Windows clients. What this means to your organization is a user will be able to log on to your network from any workstation and have access to all shared folders, files and printers.

The first step to unified login starts by configuring Samba as a primary domain controller (PDC). The full configuration details on how to set up Samba as your PDC are outside the scope of this article. Please visit the Idealx Web site for a great HOWTO (see Resources). The folks at Idealx have made great contributions to the Samba Project, and you should become familiar with their tools if you plan on using Samba.

Assuming you already have experience with setting up Samba domain controllers, this Samba configuration file should get you up and running with our directory example in the article (Listing 5). The full file is available from the Linux Journal FTP site (see Resources).

[global]

...
  obey pam restrictions = No
  ldap passwd sync = Yes
  ldap passwd sync = Yes
...
  passdb backend = ldapsam:ldap://ldapserver.foo.com/
  ldap admin dn = cn=Manager,dc=foo,dc=com
  ldap suffix = dc=foo,dc=com
  ldap group suffix = ou=Groups
  ldap user suffix = ou=People
  ldap machine suffix = ou=Computers
  ldap idmap suffix = ou=People
  ldap ssl = no
  add user script = \
    /usr/local/sbin/smbldap-useradd -m "%u"
  ldap delete dn = Yes
  delete user script = \
    /usr/local/sbin/smbldap-userdel "%u"
  add machine script = \
    /usr/local/sbin/smbldap-useradd -w "%u"
  add group script = \
    /usr/local/sbin/smbldap-groupadd -p "%g"
  delete group script = \
    /usr/local/sbin/smbldap-groupdel "%g"
  add user to group script = \
    /usr/local/sbin/smbldap-groupmod -m "%u" "% g"
  delete user from group script = \
    /usr/local/sbin/smbldap-groupmod -x "% u" "%g"
  set primary group script = \
    /usr/local/sbin/smbldap-usermod -g "%g" "%u "

The remaining piece of the puzzle involves setting up LDAP to take advantage of Samba's advancements made in the past couple of years. This should be similar to the LDAP setup above, but with updated features added in for Samba. With the new Samba 3 version, we now are able to store all Samba account information inside the LDAP directory. This is beneficial because now all the information is stored in a centralized location.

One difference in the LDAP/Samba combination setup is the additional accounts and LDAP entries that need to be populated for the two to work together. Several well-known Windows domain user accounts and domain group accounts are required for your unified login server to function. Special LDAP OU entries also are required for the server to store domain account information. Fortunately, a script called smbldap-populate is available that does all of this for you. This script is part of the Idealx smbldap-tools package that can aid you in setting up both your PDC and your Samba Enabled LDAP directory. Listing 6 is sample output of what you should see when you run the smbldap-populate script.