Introduction

Solaris LDAP naming services can use the LDAP repository in two different ways. One is as a source of both a naming service and an authentication service. The other is strictly as the source of naming data. This section discusses the concepts of client identity, authentication methods, pam_ldap and pam_unix modules, and account management when the LDAP repository is used as both a naming service and authentication service. This section also discusses the use of LDAP naming services in conjunction with the Kerberos environment (Part VI, Kerberos Service, in System Administration Guide: Security Services) and pam_krb5(5) modules.

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

If you use Kerberos as your authentication system and integrate it with the LDAP naming system, you will be able to support a single sign on (SSO) environment in your enterprise through Kerberos. You will also be able to use that same identity system when querying LDAP naming data on a per-user or per-host basis.

To access the information in the LDAP repository, clients can first establish identity with the directory server. This identity can be either anonymous or as an object recognized by the LDAP server. Based on the client's identity and the server's access control information (ACI), the LDAP server will allow the client to read or write directory information. For more information on ACIs, consult the Administration Guide for the version of Sun Java System Directory Server that you are using.

If the client is connecting as anything other than anonymous for any given request, the client must prove its identity to the server using an authentication method supported by both the client and the server. Once the client has established its identity, it can then make the various LDAP requests.

When you use pam_ldap there is a distinction between how the naming service and the authentication service (pam_ldap) access the directory. The naming service reads various entries and their attributes from the directory based on predefined identity. The authentication service establishes whether the user has entered the correct password by using that user's name and password to authenticate to the LDAP server. See the pam_ldap(5) man page for more information about the authentication service.

When Kerberos is used to perform authentication, and when authentication in LDAP naming services is also enabled (as is required for per-user mode), Kerberos can provide dual functions. Kerberos authenticates to the server and the Kerberos identity for the principal (user or host) is used to authenticate to the directory. In this way, the same user identity that is used to authenticate to the system is also used to authenticate to the directory for lookups and updates. Administrators can use access control information (ACI) in the directory to limit the results out of the naming service if desired.