LDAP second search thrown exception for different context

Question

I'm implementing a LAD request using ASP.Net. I have this method that the first time it's called, works as a charm:

public static ADUser GetUser(string userName)
{
    using (var context = new PrincipalContext(ContextType.Domain, ActiveDirectoryHelper.ApplicationDomain))
    {
        using (var searcher = new DirectorySearcher())
        {
            var internalUserName = userName.Replace("@" + ActiveDirectoryHelper.ApplicationDomain, "");
            var filter = string.Format("(&(objectCategory=person)(objectClass=user)(anr={0}))", internalUserName);
            searcher.Filter = filter;

            var user = searcher.FindOne();

            var adUser = MapToUserModel(user);
            return adUser;
        }
    }
}

Afterward, it's throwning the following exception using exactly the same filter:

000004DC: LdapErr: DSID-0C0906E8, comment: In order to perform this operation a successful bind must be completed on the connection., data 0, v1db1

Esteban Esteban · Accepted Answer · 2017-05-22T14:00:07

I don't think the error comes from the code you pasted.

This LDAP error implies that you are not bind to the server, and so cannot perform the operation.

In LDAP you have to :

Connect (as in network connection) to the server
Authenticate to the server (with a bind operation)

before making a request.

After that, if you close the bound session, you have to rebind to perform another operation or do not unbind after the first one if you have multiple operations to perform.

LDAP is a stateful protocol which means that after connect + bind is done, you are in a session where you can perform as much operations as you want without rebinding/reconnecting.

LDAP second search thrown exception for different context

2 Answers