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How to check the LDAP connection from a client to server. I'm working on the LDAP authentication and this client desktop needs to authenticate via a LDAP server. I can SSH to the LDAP server using LDAP user but When in desktop login prompt, I can't login. It says Authentication failure.

Client machine has Cent OS 6.3 and LDAP server has Cent OS 5.5

LDAP software is Openldap.

LDAP servers logs doesn't even show any messages.

So, how to test whether the client can successfully connect to LDAP or not.

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up vote 16 down vote accepted

Use ldapsearch. It will return an error if you cannot query the LDAP Server.

The syntax for using ldapsearch:

ldapsearch -x -LLL -h [host] -D [user] -w [password] -b [base DN] -s sub "([filter])" [attribute list]

A simple example

$ ldapsearch -x -LLL -h -D user -w password -b"dc=ad,dc=example,dc=com" -s sub "(objectClass=user)" givenName

Please see this link:

Edit: It seems you don't have pam configured corectlly for gdm/xdm here is an example how to do it:

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I'm using this command: ldapsearch -h hostname -x -b "dc=example,dc=com" 'uid=user' and it returns that user info from the LDAP database. But I'm not able to login to the desktop via LDAP authentication. – FELDAP Nov 28 '12 at 10:46
If your server doesn't have any error, then probably is from your client. Please take a look on the auth.log and see what is there related to ldap. – Sacx Nov 28 '12 at 10:48
Yes, I guess its the client. Its not even searching for the LDAP server. What should be done to make the client to lookup LDAP server for authentication? I have edited the /etc/pam.d/system-auth. You can check here: – FELDAP Nov 28 '12 at 11:14
Use ldapwhoami with correct parameters and try to authenticate with your user. – Sacx Nov 28 '12 at 11:16
do you followed a tutorial to prepare the client for gdm/xdm authentication ? – Sacx Nov 28 '12 at 11:21

Your problem is not LDAP, It's PAM.

As noted in the comments on Sacx's answer you probably do not have the console login application (usually the PAM system, xdm, gdm, etc. service(s)) configured to consult LDAP for authenticating users.

You should review the PAM documentation for more information on how to set this up.

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I have already configured those files, yet its not working. You can check the files I posted in the above comments. LDAP really lacks its documents. – FELDAP Dec 2 '12 at 7:25

To know if my server and clients settings are correct I use this:

ldapsearch -x -b "uid=username,ou=people,dc=example,dc=com"

the answer will be something like this on success:

# extended LDIF
# LDAPv3
# base <uid=username,ou=people,dc=example,dc=com> with scope subtree
# filter: (objectclass=*)
# requesting: ALL

# username, people,
dn: uid=username,ou=people,dc=example,dc=com
cn: User Name
uid: username
uidNumber: 1050
loginShell: /bin/bash
homeDirectory: /home/webminder
gidNumber: 1030
objectClass: posixAccount
objectClass: shadowAccount
objectClass: person
objectClass: inetOrgPerson
gecos: User Name
sn: User Name

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

you can use different filters. I only have one server on my network

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