One Of the roles in windows 2008 R2 related to UNIX systems is the identity management. windows 2008 R2 Identity Management for UNIX (and its sub roles) designed to imitate Single Sign on service to support one access to several different resources located in different environments.
Adding the roles is simple:

1.Open server management

2.Right click “Active Directory Domain Services” role, < select “Add Role services”.
< Check to add “Identity Management for UNIX” < make sure the selection add 3 more sub roles called: “Server for Network Information Services”, “Password Synchronization”, and “Administrative Tools”.

Server for Network Information Services allows the active directory to communicate with a UNIX server by exporting Network Information Services domain maps to Active directory entries, so that Active directory DC can perform as a network information service server.
While the connection to the UNIX server established, Configuring  Password  sync  for the site can be done as follows:
To set up this connection, perform the following steps:

1.Go to “Start” < “All programs” < “Microsoft identity management for UNIX” < open the program.

2.Browse to “Password Synchronization” < “UNIX based computers”.

3.Right click “UNIX based computers” < “Add computer”.

4.Insert the computer name < modify the “sync password” method configurations <
Insert the port number for password syncing < insert the right key for encryption (or generate one – you’ll have to configure the Unix server with this password as well).

5.Click “OK”.