Pam unix vs. pam ldap
From Brandonhutchinson.com
(Difference between revisions)
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** [http://docs.sun.com/app/docs/doc/816-4556/6maort2u1?a=view An example pam.conf file for pam_ldap (Solaris 10)] | ** [http://docs.sun.com/app/docs/doc/816-4556/6maort2u1?a=view An example pam.conf file for pam_ldap (Solaris 10)] | ||
| - | == | + | == Authentication walk-through == |
| - | A user attempts to login to a host using ssh and is prompted for a password. | + | A user attempts to login to a host using ''ssh'' and is prompted for a password. |
$ '''ssh user@host''' | $ '''ssh user@host''' | ||
Password: | Password: | ||
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What happens next? | What happens next? | ||
| - | === | + | === ''pam_unix'' === |
| - | *An LDAP search is performed in the | + | *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 | + | * If an entry is found, the password specified on the command line is hashed with ''crypt()'' and compared with the ''userPassword'' attribute. 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 | + | * 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. | * 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. | ||
Revision as of 21:56, 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:
- The proxy agent (e.g., cn=proxyagent,ou=profile,dc=example,dc=com) does not need read and search privileges for the userPassword attribute.
- 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.
Authentication walk-through
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 password specified on the command line is hashed with crypt() and compared with the userPassword attribute. 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.
