windows - AWS Active Directory LDAPS "cannot open connection" via ldap.exe tool

Question

I receive the following error message when trying to connect via 636 to the device below. A dialogue box comes up with "cannot open connection". The LDAP tool works fine with port 389.

Does anybody know what this is likely to be? See screenshot below. For the record, I am using AWS Managed AD.

ld = ldap_sslinit("WIN-TABC3JEHV2S.dev.test.local", 636, 1);
Error 81 = ldap_set_option(hLdap, LDAP_OPT_PROTOCOL_VERSION, 3);
Error 81 = ldap_connect(hLdap, NULL);
Server error: <empty>
Error <0x51>: Fail to connect to WIN-TABC3JEHV2S.dev.test.local.

Please note I have added a substitute name in the code snippet above due to sensitivity which is why it differs from the screenshot.

The server I am using the LDAP tool on returns a warning message Event ID 6038 relating to NTLM.

But the CA server is returning Event ID Warning 8018 and Error 10016. See below

SUBORDINATECA   8018    Warning Microsoft-Windows-DNS Client Events System  1/11/2021 12:59:23 PM

SUBORDINATECA   10016   Error   Microsoft-Windows-DistributedCOM    System  1/11/2021 12:47:07 PM

Answer 1

You need to check the windows event viewer to get more details about the error reason

Event Viewer >> System Log

http://vcloud-lab.com/entries/active-directory/ldp-exe-ldaps-cannot-open-connection-error-81