Issues Establishing Communication Between Linux-Based LDAPS Server and PLC PPC80

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1

Hi everyone,

We have successfully configured LDAPS communication when using a Windows server as the LDAP server. However, we are struggling to establish communication between a Linux-based LDAPS server and our PLC PPC80.

Setup:

Linux Server: Ubuntu 24.04 running a 389 LDAPS server
The server seems to function properly , as we can authenticate against it using other applications with the same base64 encoded certificates .
The User Location DN is correctly set up.

What we’ve tested:

On the PLC PPC80 side, we verified connectivity using the IcmpPing() function, confirming the server is reachable by both IP address and DN .
This suggests that the HOST configuration on the PLC side is correct.

Problem:

Despite confirming connectivity, communication between the PLC PPC80 and the Linux-based LDAPS server still fails. We haven’t been able to identify the root cause.
Question:

Are there any proven procedures, projects, or configurations that we can follow to resolve this issue?

Any advice or troubleshooting steps would be greatly appreciated!

Thanks in advance for your help!

2

Hi,

first I have to say, that I haven’t any practical experience with LDAPS (not Linux nor Windows).

Nevertheless I’ve some questions:
as I understood you’re using the 389 Directory Server.
I’ve seen in the help, that the root certificate authority certificate of the server must be used, and if using 389 Directory Server, the certificate has to be in “.pem” format (not “.cer” or “.crt”). Additionally, a plugin called “MemberOfPlugin” has to be enabled inside the 389 Directory Server (see here at the bottom of the page under 389 directory server). Also, the server has to support TLS1.2 or above.
Does that match to your setup?
Are there any entries in the PLC logger facing into direction of the user management (I think they would in the “Services” logger as they are generated by mpUserX)?

Best regards!