I’m not sure I fully understand your question. Do you have several Linux boxes running on the same network and your trying to synch up the username and password information on all of them?
If so, you could use a NIS server on the main Linux server. Add references to the /etc/passwd file of each client RH box to refer login information to the server. Remember; enter the reference to the NIS domain AFTER you enter the local machines root user data. If the NIS is unavailable for some reason, you’ll still want to get into the individual workstation.
This topic is far to complicated to fully explain here and anyone who attempts to do so will be doing you a disservice. You can find detailed information in chapter 12 of “Red Hat Linux 6 Unleashed”, a Sams publication, ISBN# 0-672-31689-7
An NIS domain can be used for a lot more than just password synch. A good reference will explain it in full.
If your looking to set up Linux as a domain controller for a Windows network