Difference between revisions of "OpenLDAP Authentication"

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[[Category:Networking]] [[Category:Security]]
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#REDIRECT [[LDAP Authentication]]
{{Out of date|pam_ldap/nss_ldap are deprecated in favor of {{pkg|nss-pam-ldapd}}; {{pkg|pambase}} obsoletes most of the pam section}}
 
{{Merge|LDAP Authentication}}
 
== Introduction and Concepts ==
 
 
 
This is a guide on how to configure an Arch Linux installation to authenticate against an LDAP directory. This LDAP directory can be either local (installed on the same computer) or network (e.g. in a lab environment where central authentication is desired).
 
 
 
The guide will be divided in two parts. The first part deals with how to setup an [[OpenLDAP]] server that hosts the authentication directory. The second part deals with how to setup the NSS and PAM modules that are required for the authentication scheme to work on the client computers. If you just want to configure Arch to authenticated against an already existing LDAP server then you can skip to the second part.
 
 
 
=== NSS and PAM ===
 
NSS (which stands for Name Service Switch) is a system mechanism to configure different sources for common configuration databases. For example, {{ic|/etc/passwd}} is a {{ic|file}} type source for the passwd database.
 
 
 
PAM (which stands for Pluggable Authentication Module) is a mechanism used by Linux (and most *nixes) to extend its authentication schemes based on different plugins.
 
 
 
So to summarize, we need to configure NSS to use the OpenLDAP server as a source for the {{ic|passwd}}, {{ic|shadow}} and other configuration databases and then configure PAM to use these sources to authenticate it's users.
 
 
 
== OpenLDAP Setup ==
 
 
 
=== Installation ===
 
 
 
You can read about installation and basic configuration in the [[OpenLDAP]] article. After you have completed that, return here.
 
 
 
=== Populate LDAP Tree with Base Data ===
 
 
 
Create a file called {{ic|base.ldif}} with the following text:
 
 
 
# example.org
 
dn: dc=example,dc=org
 
objectClass: dcObject
 
objectClass: organization
 
o: Example Organization
 
dc: example
 
 
# Manager, example.org
 
dn: cn=Manager,dc=example,dc=org
 
cn: Manager
 
description: LDAP administrator
 
roleOccupant: dc=example,dc=org
 
objectClass: organizationalRole
 
objectClass: top
 
 
# People, example.org
 
dn: ou=People,dc=example,dc=org
 
ou: People
 
objectClass: top
 
objectClass: organizationalUnit
 
 
# Group, example.org
 
dn: ou=Group,dc=example,dc=org
 
ou: Group
 
objectClass: top
 
objectClass: organizationalUnit
 
 
 
Add it to your OpenLDAP Tree:
 
 
 
$ ldapadd -D "cn=Manager,dc=example,dc=org" -W -f base.ldif
 
 
 
Test to make sure the data was imported:
 
 
 
$ ldapsearch -x -b 'dc=example,dc=org' '(objectclass=*)'
 
 
 
 
 
== Client Setup ==
 
 
 
[[pacman|Install]] {{Pkg|openldap}} from the [[official repositories]]. This is needed regardless of whether you run openldap on your machine or over the network.
 
 
 
Next, [[pacman|install]] {{AUR|nss-pam-ldapd}} from the [[Arch User Repository]].
 
 
 
There is the {{pkg|nss_ldap}} and {{pkg|pam_ldap}} from the [[Official Repositories|official repositories]]
 
 
 
=== OpenLDAP ===
 
Before you begin setting up PAM and NSS for ldap authentication, you should try to check if the LDAP server is available. You can do this easily with ldapsearch.
 
 
 
You can search an LDAP server with the following command:
 
{{bc|ldapsearch -x -H <URL> -b <BASE>}}
 
{{Tip| {{ic|-x}} is required in all client commands because SASL authentication probably hasn't been configured.}}
 
 
 
You can add the URL and BASE settings to {{ic|/etc/openldap/ldap.conf}} in order to avoid writing the everytime. All client-side ldap utilities use this file to read some general variables.
 
{{Warning| If you created a self-signed certificate above you need to also add the following line or you will not be able connect to the server:
 
{{ic|TLS_REQCERT allow}} }}
 
 
 
=== NSS Configuration ===
 
NSS is a system facility which manages different sources as configuration databases. For example {{ic|/etc/passwd}} is i {{ic|file}}-type source for the {{ic|passwd}} which by default stores the user accounts. nss_ldap is a plugin which allow NSS to see an OpenLDAP server as a source for these databases.
 
 
 
Edit {{ic|/etc/nsswitch.conf}} which is the central configuration file for NSS. It tells NSS which sources to use for which system databases. We need to add the {{ic|ldap}} directive to the {{ic|passwd}}, {{ic|group}} and {{ic|shadow}} databases, so be sure your file looks like this:
 
 
 
passwd: files ldap
 
group: files ldap
 
shadow: files ldap
 
 
 
==== Name Service Cache Daemon ====
 
NSCD is a daemon that NSS runs that is responsible for caching lookups and queries for network backends.
 
 
 
{{Note|It is recommended to stop the daemon when troubleshooting because it may mask problems by serving cached queries}}
 
 
 
READ THIS FIRST: [[https://bbs.archlinux.org/viewtopic.php?id=9401 NSCD Bugged in Arch Linux]]
 
Fix nscd:
 
 
 
mkdir -p /var/db/nscd/
 
mkdir -p /var/run/nscd/
 
 
 
Run nscd:
 
# systemctl start nscd
 
 
 
==== NSLCD ====
 
 
 
=== PAM Configuration ===
 
 
 
Edit {{ic|/etc/pam.d/login}}:
 
 
 
auth            requisite      pam_securetty.so
 
auth            requisite      pam_nologin.so
 
auth            sufficient      pam_ldap.so             
 
auth            required        pam_env.so
 
auth            required        pam_unix.so nullok try_first_pass
 
account        sufficient      pam_ldap.so
 
account        required        pam_access.so
 
account        required        pam_unix.so
 
session        required        pam_motd.so
 
session        required        pam_limits.so
 
session        optional        pam_mail.so dir=/var/spool/mail standard
 
session        optional        pam_lastlog.so
 
session        required        pam_unix.so
 
 
 
Edit {{ic|/etc/pam.d/passwd}}:
 
 
 
password        sufficient      pam_ldap.so
 
password        required        pam_unix.so shadow md5 nullok
 
 
 
Edit {{ic|/etc/pam.d/shadow}}:
 
 
 
auth            sufficient      pam_ldap.so
 
auth            sufficient      pam_rootok.so
 
auth            required        pam_unix.so
 
account        sufficient      pam_ldap.so
 
account        required        pam_unix.so
 
session        sufficient      pam_ldap.so
 
session        required        pam_unix.so
 
password        sufficient      pam_ldap.so
 
password        required        pam_permit.so
 
 
 
edit {{ic|/etc/pam.d/su}}:
 
 
 
auth            sufficient      pam_ldap.so
 
auth            sufficient      pam_rootok.so
 
auth            required        pam_unix.so use_first_pass
 
account        sufficient      pam_ldap.so
 
account        required        pam_unix.so
 
session        sufficient      pam_ldap.so
 
session        required        pam_unix.so
 
 
 
edit {{ic|/etc/pam.d/sshd}}:
 
 
 
auth            sufficient      pam_ldap.so
 
auth            required        pam_securetty.so        #Disable remote root
 
auth            required        pam_unix.so try_first_pass
 
auth            required        pam_nologin.so
 
auth            required        pam_env.so
 
account        sufficient      pam_ldap.so
 
account        required        pam_unix.so
 
account        required        pam_time.so
 
password        sufficient      pam_ldap.so
 
password        required        pam_unix.so
 
session        required        pam_unix_session.so
 
session        required        pam_limits.so
 
 
 
edit {{ic|/etc/pam.d/other}}:
 
 
 
auth            sufficient      pam_ldap.so
 
auth            required        pam_unix.so
 
account        sufficient      pam_ldap.so
 
account        required        pam_unix.so
 
password        sufficient      pam_ldap.so
 
password        required        pam_unix.so
 
session        required        pam_unix.so
 
 
 
== Resources ==
 
[http://arthurdejong.org/nss-pam-ldapd/setup The official page of the nss-pam-ldapd packet]
 
 
 
The PAM and NSS page at the Debian Wiki [http://wiki.debian.org/LDAP/NSS 1] [http://wiki.debian.org/LDAP/PAM 2]
 
 
 
[http://www.fatofthelan.com/articles/articles.php?pid=24 Using LDAP for single authentication]
 
 
 
[http://www.cs.dixie.edu/ldap/ Heterogeneous Network Authentication Introduction]
 
 
 
[http://readlist.com/lists/suse.com/suse-linux-e/36/182642.html Discussion on suse's mailing lists about nss-pam-ldapd]
 

Revision as of 00:59, 6 November 2013