Enable LDAPS on Active Directory by Installing Microsoft AD Certificate Services (AD CS)
LDAPS (LDAP over SSL/TLS, TCP 636) requires each Domain Controller to possess a valid Server Authentication certificate trusted by the domain. This solution enables LDAPS by installing Microsoft Active Directory Certificate Services (AD CS) and issuing LDAPS-compatible certificates to all Domain Controllers.
This approach is recommended for environments using Quest products such as Migrator Pro for Active Directory, Directory Sync Pro, Password Propagation Service (PPS), On Demand Migration agents, and other LDAP-based integrations.
Step 1 — Install the AD CS Role
Install the Certification Authority role on a domain-joined server. A member server is preferred, but installation on a Domain Controller is supported.
Step 2 — Configure Active Directory Certificate Services
-
Open Server Manager
-
Select Configure Active Directory Certificate Services
-
Select role services:
-
Configuration settings:
-
Enterprise CA
-
Root CA
-
Create a new private key
-
Cryptography:
-
Accept default CA name and validity period
-
Complete the configuration
This creates an Enterprise Root CA automatically trusted by all domain members.
Step 3 — Create and Publish an LDAPS Certificate Template
-
Open Certification Authority
-
Right-click Certificate Templates → Manage
-
Duplicate the Computer template
-
Configure the duplicated template:
-
Save the template
-
Back in Certification Authority:
-
Right-click Certificate Templates
-
Select New → Certificate Template to Issue
-
Select Domain Controller LDAPS
Step 4 — Enroll LDAPS Certificates on Domain Controllers
On each Domain Controller:
-
Force Group Policy refresh:
-
Allow several minutes for auto-enrollment to occur
(manual enrollment via Certificates MMC may be used if auto-enrollment is disabled)
Verify the issued certificate:
Step 5 — Restart Active Directory Domain Services
LDAPS is initialized only when AD DS starts.
Alternatively, reboot the Domain Controller.
Step 6 — Validate LDAPS Functionality
Confirm LDAPS Port
Expected output:
Test Using LDP.exe
-
Run ldp.exe
-
Connection → Connect
-
Server: DC FQDN
-
Port: 636
-
Check SSL
-
Connect and Bind
A successful SSL bind confirms LDAPS is operational.
Step 7 — Firewall Validation
Ensure TCP 636 is allowed:
Quest-Specific Notes
-
Quest products require LDAPS to bind using the Domain Controller FQDN, not IP address
-
Ensure the issuing CA root certificate is trusted by:
-
Once LDAPS is available, Quest services can safely disable unsecured LDAP (TCP 389)
Common Issues and Resolution
| Issue | Cause | Resolution |
|---|
| Port 636 not listening | No valid certificate at AD DS startup | Restart NTDS or reboot |
| SSL/TLS bind failure | Missing Server Authentication EKU | Re-issue certificate |
| Certificate ignored | Installed in wrong store | Must be Local Computer → Personal |
| LDAPS works on one DC only | Cert not issued to all DCs | Enroll on each DC |
| Bind fails using IP | Certificate name mismatch | Use DC FQDN only |
Result
LDAPS is now enabled and available on all Domain Controllers using certificates issued by the internal Enterprise CA. Secure LDAP connections can be established using: