I have to write a network server application which mantains a user/password list. I haven't started writing, I am still designing it, but I have thought of Java as, being a server, the more platforms it works on, the better, in addition to the rest of Java benefits. But the application needs to synchronize its user/password list with the the operating system user database. Windows 2000/XP/2003 Server user database synchronization is mandatory, and Windows NT 4 and Linux/Unix/*BSD is also important, but it could be sacrificed, depending on the difficulty, time needed/available and libraries available for it.
My questions are: How do I access the user database of the three operating system families I mentioned above from Java? is there a class or library that does this in a platform-independent way? if not, what are the best libraries for each OS family? or is there a way to do it with the Java API?.
As a last option, I could accept discarding multiplatform support and using C#, just in case .NET libraries have very good support for this, and Java a very bad one.