Difference between revisions of "OpenLDAP Authentication"

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#REDIRECT [[LDAP authentication]]
== Introduction and Concepts ==
 
 
 
This guide is composed from bits and pieces of LDAP guides and forums around the net. I borrowed very heavily from Eliott's (cactus) OpenLDAP guide [[http://solarblue.net/docs/ldap.htm Ldap Server Setup]] which is very well written. Unfortunately Arch Linux has some differences in the way things are setup. It is also the case that most LDAP guides online fall into one of 3 categories: too general, outdated or uses distro specific tools (i.e. authconfig). This guide is written specifically with Arch linux in mind and will try to illustrate both LDAP concepts and implementation from the point of view of someone who has never used LDAP before (i.e. the author).
 
 
 
=== OpenLDAP ===
 
 
 
UNDER CONSTRUCTION!
 
 
 
=== NSS and PAM ===
 
 
 
UNDER CONSTRUCTION!
 
 
 
== Server Setup ==
 
 
 
=== Install OpenLDAP ===
 
 
 
The OpenLDAP server (slapd) and clients are bundled together in the openldap package.
 
 
 
pacman -S openldap
 
 
 
=== Configure OpenLDAP ===
 
 
 
Generate root password:
 
 
 
slappasswd -h {SSHA}
 
 
 
Edit /etc/openldap/slapd.conf
 
 
 
: At a minimum your slapd.conf file should include these settings:
 
include    /etc/openldap/schema/core.schema
 
include    /etc/openldap/schema/cosine.schema
 
include    /etc/openldap/schema/inetorgperson.schema
 
pidfile    /run/openldap/slapd.pid
 
argsfile    /run/openldap/slapd.args
 
database    bdb
 
suffix      "dc=example,dc=org"
 
rootdn      "cn=Manager,dc=example,dc=org"
 
rootpw      {SSHA}AAAABBBBCCCCDDDD            #NOTE: paste in the output of the slappasswd command above 
 
directory  /var/lib/openldap/openldap-data
 
index      objectClass    eq
 
 
 
Provide a database config:
 
cp /etc/openldap/DB_CONFIG.example /var/lib/openldap/openldap-data/DB_CONFIG
 
 
 
Start OpenLDAP:
 
 
 
/etc/rc.d/slapd start
 
 
 
Alternatively:
 
# rc.d start slapd
 
 
 
=== Populate LDAP Tree with Base Data ===
 
 
 
Create a file called 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 -x -D "cn=admin,dc=example,dc=org" -W -f base.ldif
 
 
 
Test to make sure the data was imported:
 
 
 
ldapsearch -x -b 'dc=example,dc=org' '(objectclass=*)'
 
 
 
=== Configure TLS Encryption ===
 
 
 
It's a good idea to configure TLS to encrypt the exchange of information between client and server. This way passwords, which are normally sent plain-text, cannot be easily sniffed from the wire. In order to use TLS, we must first create a certificate. You can have a certificate signed, or create your own Certificate Authority (CA), but for our purposed, a self-signed certificate will suffice. '''IMPORTANT:''' OpenLDAP cannot use a certificate that has a password associated to it.
 
 
 
To create a ''self-signed'' certificate, type the following:
 
 
 
openssl req -new -x509 -nodes -out slapdcert.pem -keyout slapdkey.pem -days 365
 
 
 
You will be prompted for information about your ldap server. Much of the information can be left blank. The most important information is the common name. This must be set to the DNS name of your ldap server. If your LDAP server's IP address resolves to example.org but its server certificate shows a CN of bad.example.org, LDAP clients will reject the certificate and will be unable to negotiate TLS connections (apparently the results are wholly unpredictable).
 
 
 
Now that the certificate files have been created copy them to /etc/openldap/ssl/ (if this directory doesn't exist create it) and secure them. '''IMPORTANT:''' slapdcert.pem must be world readable because it contains the public key.
 
 
 
cp slapdcert.pem slapdkey.pem /etc/openldap/ssl/
 
chmod 400 slapdkey.pem
 
chmod 444 slapdcert.pem
 
 
 
Edit the daemon configuration file (/etc/openldap/slapd.conf) to tell LDAP where the certificate files reside by adding the following lines:
 
 
 
# Certificate/SSL Section
 
TLSCipherSuite HIGH:MEDIUM:+SSLv2
 
TLSCertificateFile /etc/openldap/ssl/slapdcert.pem
 
TLSCertificateKeyFile /etc/openldap/ssl/slapdkey.pem
 
 
 
The TLSCipherSuite specifies a list of OpenSSL ciphers from which slapd will choose when negotiating TLS connections, in decreasing order of preference. In addition to those specific ciphers, you can use any of the wildcards supported by OpenSSL. '''NOTE:''' HIGH, MEDIUM, and +SSLv2 are all wildcards.
 
 
 
To see which ciphers are supported by your local OpenSSL installation, type the following:
 
 
 
openssl ciphers -v ALL
 
 
 
In order to tell OpenLDAP to start using encryption, edit /etc/conf.d/slapd, uncomment the SLAPD_SERVICES line and set it to the following:
 
 
 
SLAPD_SERVICES="ldaps:///"
 
 
 
This will cause OpenLDAP to accept encrypted. '''IMPORTANT:''' If you created a self-signed certificate above be sure to add the following line to /etc/openldap/ldap.conf or you won't be able connect to the server to test it:
 
 
 
TLS_REQCERT allow
 
 
 
Restart the server:
 
 
 
/etc/rc.d/slapd restart
 
 
 
Test that the server is encrypting traffic run the following command:
 
 
 
ldapsearch -x -H ldaps://example.org -b 'dc=example,dc=org' '(objectclass=*)'
 
 
 
== Client Setup ==
 
 
 
=== OpenLDAP ===
 
 
 
'''IMPORTANT:''' If you created a self-signed certificate above be sure to add the following line to /etc/openldap/ldap.conf or you won't be able connect to the server:
 
 
 
TLS_REQCERT allow
 
 
 
 
 
=== NSS_LDAP ===
 
 
 
Install the nss_ldap module:
 
 
 
pacman -S nss_ldap
 
 
 
Edit /etc/nss_ldap.conf:
 
 
 
host <SERVER_IP>
 
base dc=example,dc=org
 
rootbinddn cn=admin,dc=example,dc=org
 
port 636
 
pam_login_attribute uid
 
pam_template_login_attribute uid
 
nss_base_passwd ou=People,dc=example,dc=org?one
 
nss_base_shadow ou=People,dc=example,dc=org?one
 
nss_base_group  ou=Group,dc=example,dc=org?one
 
ssl start_tls
 
ssl on
 
 
# This is only needed if your using a self-signed certificate.
 
tls_checkpeer no
 
 
 
Edit /etc/nsswitch.conf
 
 
 
passwd: files ldap
 
group: files ldap
 
shadow: files ldap
 
 
 
=== PAM_LDAP ===
 
 
 
Install pam_ldap module:
 
 
 
pacman -S pam_ldap
 
 
 
Edit /etc/pam_ldap.conf:
 
 
 
host <SERVER_IP>
 
base dc=example,dc=org
 
rootbinddn cn=admin,dc=example,dc=org
 
port 636
 
pam_login_attribute uid
 
pam_template_login_attribute uid
 
nss_base_passwd ou=People,dc=example,dc=org?one
 
nss_base_shadow ou=People,dc=example,dc=org?one
 
nss_base_group  ou=Group,dc=example,dc=org?one
 
ssl start_tls
 
ssl on
 
 
# This is only needed if your using a self-signed certificate.
 
tls_checkpeer no
 
 
 
Edit /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 /etc/pam.d/passwd:
 
 
 
password        sufficient      pam_ldap.so
 
password        required        pam_unix.so shadow md5 nullok
 
 
 
Edit /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 /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 /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 /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
 
 
 
=== Name Service Cache Daemon ===
 
 
 
READ THIS FIRST: [[http://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:
 
 
 
/etc/rc.d/nscd start
 
 
 
== Links and Resources ==
 
 
 
One of the best OpenLDAP clients: [[http://phpldapadmin.sourceforge.net/ phpLDAPadmin]]
 
 
 
Debian OpenLDAP setup: [[http://www.fatofthelan.com/articles/articles.php?pid=24 Using LDAP for single authentication]]
 
 
 
How to integrate OpenLDAP for MacOSX, Windows and Linux: [[http://www.cs.dixie.edu/ldap/ Heterogeneous Network Authentication Introduction]]
 
 
 
== Troubleshooting ==
 
If you notice that slapd seems to start but then stops, you may have a permission issue with the ldap datadir. Try running:
 
 
 
# chown ldap:ldap /var/lib/openldap/openldap-data/*
 
 
 
to allow slapd write access to its data directory as the user "ldap"
 

Latest revision as of 11:33, 13 February 2014