Fixing Active Directory Error Logon Failure - Unknown User Name Or Bad Password

Fixing System.DirectoryServices.DirectoryServicesCOMException (0x8007052E): Logon failure: unknown user name or bad password.

Recently I faced a weird issue where I was not able to run the LDAP queries using Directory Services API of .Net for other domains through legitmate user accounts. 

 

If I was logged into Domain xyz.com, and I was able to run the LDAP queries in xyz.com domain,  I was not able to run the queries on abc.com AD from xyz.com.

 

After digging and running through a few links, here is the code change that helped me fix the issue.

Before 

Check the DirectoryEntry Path properties, it's set with direct ad domain.  

using (DirectoryEntry rootEntry = new DirectoryEntry())
            {
                rootEntry.Path = $"LDAP://dc=abc,dc=com";
                rootEntry.Username = yourid;
                rootEntry.Password = yourpassword;

                using (DirectorySearcher _searcher = new DirectorySearcher(rootEntry))
                {
                    _searcher.Filter = filter;
                    _searcher.PageSize = 1000;


                   SearchResultCollection _searchResultCollections = _searcher.FindAll();
                }
            }

Fix

Changing the DirectoryEntry Path to explictly connect to the 389 port fixed the issue.

rootEntry.Path = $"LDAP://abc.com:389/dc=abc,dc=com";

Here is the MSDN article that explains in detail how the lDAP query search works, that gave me some hints. 

 

Happy coding.