System userid and Password

You cannot get the user password from the system, so you have to make a method to check if the
password typed is valid using a dll.

private int LOGON32_PROVIDER_DEFAULT = 0;
private int LOGON32_LOGON_INTERACTIVE = 2;

[DllImport("advapi32.dll")]
private static extern bool LogonUser (string lpszUsername, string lpszDomain, string lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

public bool ValidateUser(string UserName, string Pwd, string Domain)
{
IntPtr tokenHandle = IntPtr.Zero;
try
{
//Call the LogonUser function to obtain a handle to an access token.
bool returnValue = LogonUser(UserName, Domain, Pwd, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref tokenHandle);
if (!returnValue)
{
return false;
}
else
return true;
}
catch (Exception Ex)
{
throw Ex;
}
}



That should do it, if you want to get the username of the current user you can use
System.Environment.UserName instead of allowing the user to type one.

The domain you can get on 2 ways:

string Domain = System.Environment.UserDomainName;
if (Domain == "")
{
//If you don't have a domain then The MachineName property gets the name of your computer.
Domain = System.Environment.MachineName;
}


(Heh this code can use some cleaning =P)