Active Directory Alternative

[Slip]

I am currently working with a Windows 2000 Network that is is running Directory Service and is highly relied on Active Directory. If you do not know what Active Directory is, click here to learn more.

Before I do the switch I would like to find the best alternative that would achieve the same thing, any suggestions?

[Dolda2000]

Well, if you have any Windows clients, there probably aren't really any alternatives. Windows clients are rather limited, after all. You could possible do something with MS SFU, but I can't say that I know enough about Windows or SFU to tell for sure.

If you only have Linux/MacOSX/UNIX/Whatever-other-than-Windows clients, however, you can just use the individual components of AD. Since AD is basically LDAP and Kerberos, you can just install an OpenLDAP server and a Kerberos KDC on the server, and then use nss_ldap and pam_krb5 on the clients.

[nonsence]

i know it's an old post, but meh, i figure i'd put in some input.
i haven't yet done this linux/windows integration myself yet, only been reading on it. but basically since active directory is an ldap and kerberos server like the other poster said, you can get linux and unix single sign on and authentication working, but it usually involves either installing a client on the linux system, or customizing the pam authentication so it uses ldap/ssl or kerberos, or i think it should be able to do ntlm also.

http://www.centrify.com/

that's a site for the currently best method of integrating linux into active directory. but it's not free.
anything free and open source will take a bit more reading, since it's more then just a simple install.
problem is most linux distros are targetted for home users or servers. only novell and red hat are putting up a good front for corporate clients, everything else comes with the software capable of doing it, but you gotta put the peices together yourself, such as fedora core or gentoo or debian, they all are capable of authenticating to active directory but you gotta configre the ldap and kerberos clients for it