Pam unix vs. pam ldap

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* The ''userPassword'' attribute must be non-null.
* The ''userPassword'' attribute must be non-null.
* Passwords must be stored in ''{crypt}'' format on the LDAP server.
* Passwords must be stored in ''{crypt}'' format on the LDAP server.
-
* The proxy agent (e.g., ''cn=proxyagent,ou=profile,dc=example,dc=com'') must have read and search privileges for the '''userPassword''' attribute.
+
* The proxy agent (e.g., ''cn=proxyagent,ou=profile,dc=example,dc=com'') must have read and search privileges for the ''userPassword'' attribute.
* '''ldaplist -l passwd''' will return all password hashes, similar to '''ypcat passwd''' in a NIS environment.
* '''ldaplist -l passwd''' will return all password hashes, similar to '''ypcat passwd''' in a NIS environment.
* The entered password is not sent to the LDAP server.
* The entered password is not sent to the LDAP server.
 +
* The default ''/etc/pam.conf'' file is configured for ''pam_unix'' (at least on Solaris 8).
 +
Given the severe limitation of '''ldaplist -l password''' returning all password hashes, ''pam_ldap'' should be used if possible.
 +
== ''pam_ldap'' ==
-
=== pam_ldap ===
+
With ''pam_ldap'':
-
 
+
* The proxy agent (e.g., ''cn=proxyagent,ou=profile,dc=example,dc=com'') does not need read and search privileges for the ''userPassword'' attribute.
-
* The proxy agent (e.g., '''cn=proxyagent,ou=profile,dc=example,dc=com''') does not need read and search privileges for the '''userPassword''' attribute.
+
-
* The entered password is sent to the LDAP server, so encryption should be used.
+
* If the LDAP server is properly configured, '''ldaplist -l passwd''' will not return all user password hashes.
* If the LDAP server is properly configured, '''ldaplist -l passwd''' will not return all user password hashes.
 +
* The entered password is sent to the LDAP server, so encryption (e.g., TLS:Simple) should be used.
 +
* The default ''/etc/pam.conf'' will have to be modified.
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** [http://docs.sun.com/app/docs/doc/806-4077/6jd6blbg4?a=view An example pam.conf file for pam_ldap (Solaris 8 and 9)]
 +
** [http://docs.sun.com/app/docs/doc/816-4556/6maort2u1?a=view An example pam.conf file for pam_ldap (Solaris 10)]
=== Walkthrough ===
=== Walkthrough ===

Revision as of 21:43, 14 December 2007

Contents

Overview

The following notes list some differences between pam_unix and pam_ldap authentication.

pam_unix

With pam_unix:

  • The userPassword attribute must be non-null.
  • Passwords must be stored in {crypt} format on the LDAP server.
  • The proxy agent (e.g., cn=proxyagent,ou=profile,dc=example,dc=com) must have read and search privileges for the userPassword attribute.
  • ldaplist -l passwd will return all password hashes, similar to ypcat passwd in a NIS environment.
  • The entered password is not sent to the LDAP server.
  • The default /etc/pam.conf file is configured for pam_unix (at least on Solaris 8).

Given the severe limitation of ldaplist -l password returning all password hashes, pam_ldap should be used if possible.

pam_ldap

With pam_ldap:

Walkthrough

A user attempts to login to a host using ssh and is prompted for a password.

$ ssh user@host
Password:

What happens next?

pam_unix

  • An LDAP search is performed in the ou=people container for an entry that contains objectClass=shadowAccount and uid=user. The search base is the value of NS_LDAP_SEARCH_BASEDN from /var/ldap/ldap_client_file.
  • If an entry is found, the value of the userPassword attribute is compared with the password specified on the command line. If the values match, the user is authenticated.

pam_ldap

  • An LDAP search is performed in the ou=people container for an entry that contains object=posixAccount and uid=user. The search base is the value of NS_LDAP_SEARCH_BASEDN from /var/ldap/ldap_client_file.
  • If an entry is found, the client attempts to bind to the LDAP server using the Distinguished Name (DN) (e.g., uid=user,ou=people,dc=example,dc=com) and password specified on the command line. If the client is able to bind, the user is authenticated.
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