We describe user-level security first because its simpler. In user-level security, the client sends a session setup request directly following protocol negotiation. This request provides a username and password. The server can either accept or reject that username/password combination. At this stage the server has no idea what share the client will eventually try to connect to, so it can't base the accept/reject on anything other than:

If the server accepts the username/password credentials, the client expects to be able to mount shares (using a tree connection ) without further specifying a password. It expects that all access rights will be as the username/password credentials set that was specified in the initial session setup .

It is also possible for a client to send multiple session setup requests. When the server responds, it gives the client a uid to use as an authentication tag for that username/password. The client can maintain multiple authentication contexts in this way (WinDD is an example of an application that does this).

Windows networking user account names are case-insensitive, meaning that upper-case and lower-case characters in the account name are considered equivalent. They are said to be case-preserving, but not case significant. Windows and LanManager systems previous to Windows NT version 3.10 have case-insensitive passwords that were not necessarilty case-preserving. All Windows NT family systems treat passwords as case-preserving and case-sensitive.