Please help us help you and fill where relevant:
Your LimeSurvey version: 6.15.15
Own server or LimeSurvey hosting: Own Server
Survey theme/template: Default
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I’ve set up LimeSurvey on IIS in an air-gapped Windows Server 2022 environment with Active Directory and MySQL. LDAP (port 389) authentication works fine, but switching to LDAPS (636) fails with the error “Can’t contact LDAP server.”
What I’ve done so far:

• Environment:
  • VM1 – Domain Controller (dc01.survey.local) with CA installed
  • VM2 – IIS + LimeSurvey
  • VM3 – MySQL
  • VM4 – Client for testing
• Verified LDAPS from VM1:
  • ldp.exe connects successfully to dc01.survey.local:636
  • PowerShell test with [System.DirectoryServices.Protocols.LdapConnection] works
  • PHP test (openssl + ldap_connect) still fails with "Can't connect to LDAP server"
• Certificates:
  • DC has a cert issued by the internal CA using the Domain Controller template
  • Subject is empty but SAN includes dc01.survey.local, survey.local, and SURVEY
  • Verified with certutil that the CA cert is trusted on the IIS server
  • openssl_x509_parse() returns the parsed array successfully
• LimeSurvey config:
  • LDAP server: ldaps://192.168.163.129
  • Port: 636
  • LDAP version: 3
  • StartTLS: off (tested both on/off)
  • Referrals: off
  • Bind DN: CN=Administrator,CN=Users,DC=survey,DC=local
  • Base DN:CN=Users,DC=survey,DC=local
  • Attribute: sAMAccountName
    
    

All LDAPS tests from OS level succeed, but LimeSurvey cannot connect, returning “Can’t contact LDAP server.”

Has anyone successfully configured LDAPS for LimeSurvey on IIS/Windows Server with AD?

Strange
github.com/LimeSurvey/LimeSurvey/pull/4217
fix such issue.

Hi Denis, thanks for the reply.

I’ve the latest version with the PR applied (github.com/LimeSurvey/LimeSurvey/pull/4217), and I confirmed that my ldap_helper.php matches the updated code. My LDAP plugin config is also correct: use_start_tls = false, LDAPv3, port 636 for LDAPS, proper bind DN and password.

Despite this, I still can’t login via LDAPS—connections to port 636 work from the server (IIS) using PHP test scripts, and normal LDAP (389) works. 

Could anyone advise on further steps to debug or confirm LDAPS is fully functional in LimeSurvey?

Thanks in advance.

Oups,
Seems ldap_helper is used for ldap import

Here :  github.com/LimeSurvey/LimeSurvey/blob/42...AP/AuthLDAP.php#L327

Out here :  github.com/LimeSurvey/LimeSurvey/blob/42...AP/AuthLDAP.php#L346 ?