LDAP Integration Module (ldap_integration-5.x)  is a set of three modules:

• ldapauth
  It implements basic LDAP integration and sets up the environment for the other optional modules.
• ldapgroups
  Extends the basic functionality and integrates LDAP Groups into Drupal Roles
• ldapdata
  Extends the basic functionality and allows for the management of LDAP Attributes from within Drupal.

Enable ldap_inetgration in Administer >> Site building >> Modules.

Configure LDAP Server at Administer >> Site Configuration >> LDAP Integration

Enter LDAP server,port, base dn,user and mail attribute, save the configuration). So next time when user loggs in drupal will check users in LDAP.

Configure LDAP Data at Administer >> Site Configuration >> LDAP Data

Map LDAP to user profile attribute.

Configure LDAP Data at Administer >> Site Configuration >> LDAP Groups

Select “Groups exist as LDAP entries where a multivalued attribute contains the members’ Cns” and inside “Nodes containing groups (one per line):” type the name of the node where drupal groups are stored. In “Attribute holding group members: “ type “memberUid”. Save Configuration.

Configure LDAP Data at Administer >> Site Configuration >> LDAP Registration

Type server name and base-dn of the users in LDAP.