Question

I use this code:

DirectoryEntry objEntry;
DirectorySearcher objSearchEntry;
SearchResultCollection objSearchResult;
string strFilter = "(&(objectCategory=User))";
objEntry = new DirectoryEntry(conOUPath, conUser, conPwd, AuthenticationTypes.Secure);
objEntry.RefreshCache();
objSearchEntry = new DirectorySearcher(objEntry);
objSearchEntry.Filter=strFilter;
objSearchEntry.SearchScope=SearchScope.Subtree;
objSearchEntry.CacheResults=false;
objSearchResult=objSearchEntry.FindAll();

Each time, it only return 1000 users, but there are 3000 users in that OU.

How can i find all of them ?

Answer 1

If you’re on .NET 3.5 or newer, you should check out the PrincipalSearcher and a “query-by-example” principal to do your searching:

// create your domain context
PrincipalContext ctx = new PrincipalContext(ContextType.Domain, "YOURDOMAIN", "OU=SomeOU,DC=YourCompany,DC=com");

// define a "query-by-example" principal - here, we search for a UserPrincipal 
// and with the first name (GivenName) of "Bruce"
UserPrincipal qbeUser = new UserPrincipal(ctx);
qbeUser.GivenName = "Bruce";

// create your principal searcher passing in the QBE principal    
PrincipalSearcher srch = new PrincipalSearcher(qbeUser);

// set the PageSize on the underlying DirectorySearcher to get all 3000 entries
((DirectorySearcher)srch.GetUnderlyingSearcher()).PageSize = 500;

// find all matches
foreach(var found in srch.FindAll())
{
    // do whatever here - "found" is of type "Principal" - it could be user, group, computer.....          
}

If you haven’t already – absolutely read the MSDN article Managing Directory Security Principals in the .NET Framework 3.5 which shows nicely how to make the best use of the new features in System.DirectoryServices.AccountManagement

Update:

Of course, depending on your need, you might want to specify other properties on that “query-by-example” user principal you create:

• Surname (or last name)
• DisplayName (typically: first name + space + last name)
• SAM Account Name – your Windows/AD account name
• User Principal Name – your “[e-mail]” style name

You can specify any of the properties on the UserPrincipal and use those as “query-by-example” for your PrincipalSearcher.

Update #2: If you want to search just inside a given OU, you can define that OU in the constructor of the PrincipalContext.