Connecting Windows 7 computers to a standalone Lion Server running as Open Directory master:
You can lower the required security settings for Windows 7 via secpol.msc (Win 7 Pro) or editing the registry as some how-to's will suggest - this has been a suggestion made for resolving problems authenticating from Vista to earlier verions of Mac OS X Server. See mambro's post above, or
http://www.macwindows.com/OSXServer.html#050310c
In this day and age of increasing (and valid) concerns over security, many may prefer to not *decrease* the security for network authentication on their Windows workstations.
Bear in mind that the following tip is for Lion Server that is not part of an Active Directory Domain!
If that is the case with your server, stop here and do not proceed. Instead, seek out and work with your network administrar(s) and Active Directory admin(s). Your server should already have been bound to your AD domain - for example in what's known as a "Golden Triangle" setup - and you should resolve authentication issues with your admins, as your client machines should be authenticating against AD.
With a standalone setup of Lion Server (you have setup Lion server on a single Mac) promoted to an Open Directory Master, your 10.7 Server can provide Kerberos authentication for your Windows client machines. The problem is that your Win machines don't know anything about your Lion server and won't trust it as a KDC.
There is a helpful document from ncsa.illinois.edu,
https://wiki.ncsa.illinois.edu/display/ITS/Windows+7+Kerberos+Login+using+Extern al+Kerberos+KDC
which summarizes the steps you can take, of course adjusting accordingly for your own server & FQDN,
please do not use any hostnames in that article !!!
Please ensure that you have verified the Kerberos realm for your Lion server. Unless you have specified otherwise (for good reason), then it will match the FQDN (dns name) for your server, but should be written in all-caps (see http://www.afp548.com/article.php?story=20060709175021180
to learn more about Kerberos)
The key steps being (on your Win 7 workstation):
Ksetup /setdomain SERVER.YOURNAMEHERE.COM
Ksetup /addkdc SERVER.YOURNAMEHERE.COM server.yournamehere.com
After taking the steps above, and rebooting the Windows client machine,
I added one additional step from Microsoft, (please do see)
http://technet.microsoft.com/en-us/library/cc757218(WS.10).aspx
/AddKpasswd RealmName KpasswdName
thus:
Ksetup /AddKpasswd SERVER.YOURNAMEHERE.COM server.yournamehere.com
You can then connect to your Lion server via (an Explorer window) (editing accordingly for the shortname
of your server:
\\Server\Sharepointname
at which point you'll be asked to authenticate and should be able to do so successfully and connect to the sharepoint in question, as long as the user in question (that you have authenticated as), has indeed already been assigned appropriate access permissions on your server.
Other sharepoints that the same user has authorization to access on your Lion Serve, s/he should also now be able to access. Keep in mind that the default setting in Server.app (where you setup your sharepoints in Lion server) sets Read Access for "Everyone Else" - you might wish or need to change Read-Access to No Access to prevent users from seeing the sharepoint altogether.
-- David Haines (ACTC, ACSA)