Praveen Kumar writes:
I using the LDAP server for authentication and log into a machine.
Now i want the user should not be allowed log into any machine, if it is already logged into one machine using that LDAP server for the login and authentication.
Means that there should not be any simultaneous login for the same user. Is this possible using the LDAP or Not.
Not by itself. The machine uses LDAP simply to check if the username and password are correct, and perhaps get his account info. That done, it likely terminates that LDAP session though the user stays logged in on the machine. Nothing informs the LDAP server when the user logs out from the machine, so the LDAP server doesn't know when to start accepting logins for that user on that machine again.
So you need to solve this on the machine the user logs in on.
Thogh I suppose it might be possible to a Single Sign-On service in reverse somehow on your network. SSO - like Kerberos which LDAP supports via SASL - lets you login just once on your network and then logins elsewhere makes use of tickets from the first login instaed of asking for a certificate again.