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Programming AD with C#.NET – part 3

So far we have managed to exclude System.DirectoryServices because of our original issues, and System.DirectoryServices.AccountManagement because of performance issues. What is left for us now is System.DirectoryServices.Protocols, and that is the namespace of our choice.

Generally the System.DirectoryServices.Protocols is pretty similar to System.DirectoryServices, so it is not a big deal to rebuild our existing classes to a newer version. But there are always some small obsacles that need to be conquered. A very good guide to get started with these classes is written by Ethan Wilansky and published on MSDN, Introduction to System.DirectoryServices.Protocols.

An small issue is that you always have to know if an attribute exists before you try to remove it. The same thing applies when an attribute is saved, you must know if it is a new attribute to be created or an existing attribute that should be updated. If an incorrect action is taken a DirectoryOperationException will be thrown. A simple solution for this problem is to add a PermissiveModifyControl to the request. This will make sure that add, edit and remove events is handled nicely without throwing any exceptions.

Paging a search result is another thing that could be a little tricky. With System.DirectoryServices you only had to set the PageSize on a DirectorySearcher and the paging was automatically handled. With System.DirectoryServices.Protocols we have got to deal with the paging ourselves. There are a lot more information about this in the article mention above, Introduction to System.DirectoryServices.Protocols.

One third little quirk I had was when creating user accounts.We need to be able to set the password, and with System.DirectoryServices.Protocols it is possible to modify the value unicodePwd. However there are a couple of things to keep in mind.:
  • A 128 bit encrypted channel must be used.
  • The password must be a byte array containing the password surrounded by quotation marks.
Here is a simple code sample that meets both of these demands:

LdapDirectoryIdentifier identifier = new LdapDirectoryIdentifier("server");
NetworkCredential credential = new NetworkCredential("user", "password", "domain");
using(LdapConnection connection = new LdapConnection(identifier, credential))
{
    connection.SessionOptions.Signed = true;
    connection.SessionOptions.Sealed = true;
    DirectoryAttribute[] attributes = new DirectoryAttribute[] {
        new DirectoryAttribute("objectClass", "user"),
        new DirectoryAttribute("userPrincipalName", "newAdAccount@domain.com"),
        new DirectoryAttribute("samAccountName", "newAdAccount"),
        new DirectoryAttribute("unicodePwd", Encoding.Unicode.GetBytes("\"passw0rd\""))
    };
    AddRequest request = new AddRequest("CN=newAdAccount,OU=Test,DN=domain,DN=com", attributes);
    connection.SendRequest(request);
}

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