- 4 minutes to read

Securing LDAP using SSL

Secure your directory integrations by enabling SSL/LDAPS for LDAP communication. This guide shows you how to encrypt and trust connections between Nodinite LDAP products and your LDAP Catalog Service, so you achieve compliance and peace of mind.

✅ Encrypt all LDAP traffic for maximum security
✅ Follow proven certificate management best practices
✅ Achieve compliance with enterprise and regulatory requirements
✅ Use with both BizTalk LDAP Adapter and LDAP Web API

This user guide applies to both Nodinite LDAP products: BizTalk LDAP Adapter and LDAP Web API. It explains how to secure communication between the Nodinite LDAP products and your LDAP Catalog Service.

Understanding LDAPS

LDAPS (LDAP over SSL/TLS) encrypts LDAP communication using SSL/TLS certificates. When properly configured:

  • LDAP traffic uses port 636 (instead of standard LDAP port 389)
  • All communication is encrypted end-to-end
  • Certificate validation ensures you're connecting to the correct domain controller

Note

This guide focuses on Active Directory. Other LDAP services (ADAM/LDS, DirX, etc.) have similar requirements but may use different certificate stores or configuration methods.

Configuration Steps

Step 1: Install Certificate on Domain Controllers

On each Active Directory Domain Controller that clients will connect to:

  1. Obtain a certificate with the following requirements:

    • Subject or Subject Alternative Name (SAN): Must match the Domain Controller's Fully Qualified Domain Name (FQDN)
    • Enhanced Key Usage: Must include Server Authentication (OID 1.3.6.1.5.3.3.1)
    • Private key: Must be exportable (for installation on multiple DCs)
    • Certificate Authority: Use your enterprise CA or a trusted public CA

    Warning

    Self-signed certificates work for testing but are not recommended for production. Use certificates from your enterprise Certificate Authority or a trusted public CA for production environments.

  2. Install the certificate:

    • Open certlm.msc (Local Computer Certificates) on the Domain Controller
    • Navigate to Personal → Certificates
    • Import or request the certificate (ensure the private key is imported)
    • Verify the certificate appears in the Personal\Certificates store for the computer account

  3. Restart the NTDS service or reboot the Domain Controller:

    Restart-Service NTDS -Force

  4. Verify LDAPS is enabled:

    • Use ldp.exe (included with Windows Server)
    • Connection → Connect → Server: dc.yourdomain.com, Port: 636, SSL: checked
    • You should successfully connect over LDAPS

Step 2: Install Certificate on LDAP Client Servers

On the server(s) running the BizTalk LDAP Adapter and/or LDAP Web API:

  1. Export the root certificate from your Certificate Authority or Domain Controller

  2. Install on the client server:

    • Open certlm.msc (Local Computer Certificates)
    • Navigate to Trusted Root Certification Authorities → Certificates
    • Right-click → All Tasks → Import
    • Select the root certificate file
    • Complete the import wizard

  3. For certificates with intermediate CAs:

  4. Verify certificate chain:

    • Double-click the imported certificate
    • Check the Certification Path tab
    • Ensure the chain shows "This certificate is OK"

  5. Restart services or reboot if required

Step 3: Configure Connection String

Update your LDAP connection string to use LDAPS:

Before (insecure):

LDAP://dc.yourdomain.com:389

After (secure):

LDAPS://dc.yourdomain.com:636

Tip

When using LDAPS, certificate validation is automatic. Ensure the certificate's Subject Name or SAN matches the hostname in your connection string to avoid validation errors.

Troubleshooting

LDAPS Connection Fails

  • Check certificate validity: Use certlm.msc to verify the certificate hasn't expired
  • Verify port 636 is open: Use Test-NetConnection -ComputerName dc.yourdomain.com -Port 636 from the client server
  • Check certificate chain: Ensure all intermediate and root certificates are properly installed
  • Review Event Logs: Check Windows Event Viewer → System and Directory Services logs on the Domain Controller

Certificate Validation Errors

  • Hostname mismatch: The certificate's Subject Name or SAN must match the FQDN in your connection string
  • Trust chain broken: Verify all intermediate certificates are installed in the correct store
  • Certificate expired: Replace with a new certificate before the expiration date

Certificate Management Best Practices

  • Use enterprise CA: Leverage your organization's Certificate Authority for centralized management
  • Plan for renewal: Set reminders to renew certificates at least 30 days before expiration
  • Monitor certificate health: Use Nodinite monitoring agents to alert on expiring certificates
  • Document your configuration: Keep records of which certificates are deployed where
  • Test in non-production: Always validate certificate changes in dev/test environments first

References

Important

Always use certificates to secure communication. Replace certificates before they expire or become obsolete.

Next Step

Monitoring Certificates:

Nodinite Monitoring Agents