Configuring PAM to Use LDAP server_policy

To configure PAM to use LDAP server_policy, follow the sample in Example pam_conf file for pam_ldap Configured for Account Management. Add the lines that contain pam_ldap.so.1 to the client's /etc/pam.conf file. In addition, if any PAM module in the sample pam.conf file specifies the binding flag and the server_policy option, use the same flag and option for the corresponding module in the client's /etc/pam.conf file. Also, add the server_policy option to the line that contains the service module pam_authtok_store.so.1.

Previously, if you enabled pam_ldap account management, all users needed to provide a login password for authentication any time they logged in to the system. Therefore, nonpassword-based logins using tools such as rsh, rlogin, or ssh would fail.

Now, however, pam_ldap(5), when used with Sun Java System Directory Servers DS5.2p4 and newer releases, enables users to log in with rsh, rlogin, rcp and ssh without giving a password.

pam_ldap(5) is now modified to perform account management and retrieve the account status of users without authenticating to Directory Server as the user logging in. The new control to this on Directory Server is 1.3.6.1.4.1.42.2.27.9.5.8, which is enabled by default.

To modify this control for other than default, add Access Control Instructions (ACI) on Directory Server:

dn: oid=1.3.6.1.4.1.42.2.27.9.5.8,cn=features,cn=config
objectClass: top
objectClass: directoryServerFeature
oid:1.3.6.1.4.1.42.2.27.9.5.8
cn:Password Policy Account Usable Request Control
aci: (targetattr != "aci")(version 3.0; acl "Account Usable"; 
     allow (read, search, compare, proxy)
     (groupdn = "ldap:///cn=Administrators,cn=config");)
creatorsName: cn=server,cn=plugins,cn=config
modifiersName: cn=server,cn=plugins,cn=config

• The binding control flag

  Using the binding control flag allows a local password override of a remote (LDAP) password. For example, if a user account is found on both the local files and the LDAP namespace, the password associated with the local account takes precedence over the remote password. Thus, if the local password expires, authentication fails even if the remote LDAP password is still valid.

• The server_policy option

  The server_policy option instructs pam_unix_auth, pam_unix_account, and pam_passwd_auth to ignore a user found in the LDAP namespace and to allow pam_ldap to perform authentication or account validation. In the case of pam_authtok_store, a new password is passed to the LDAP server without encryption. The password is thereby stored in the directory according to the password encryption scheme configured on the server. For more information, see pam.conf(4) and pam_ldap(5).