The LDS is available from the OPC Foundation (easy to download).
The CTT can be used in client mode to adjust what message and responses are provided.
is this enough information for you?

Thanks for your response.

Well, I need more precisions since I do not manage to use the CTT as a man in the middle for server testing purpose.

I installed the UA LDS of the OPCUA fondation V1.4.403.81. I'me currently using the CCT V1.4.9.398.

I managed to use the CTT for my OPCUA client testing but not for the server.

What I want is to manipulate messages sent back to the server when this one is triying to register itself to the ualds.
In CTT server project, there is a discovery section but it's used only to browse the server.
In CTT client server, we can specify the Underlying Server URL and Endpoint URL. Then I concluded that I have to use CTT client project to test the server on its registration to the lds (since the server is client in this case).
Then I tried to put the lds configuration endpoint. For instance:
Underlying Server URL: opc.tcp://localhost:4840
Endpoint URL: opc.tcp://localhost:4841
On my server, configured it to register itself on the endpoint: opc.tcp://localhost:4841

But when I watch the logs, it seems that the CTT is not able to make it runs. There is no trace, no error and in my server logs and lds logs I have no trace of connection attemps. Only timeout response on my server registration request.

Did I miss something ? Where am I wrong ?

Thanks for your help

Best regards

Grégoire GUILLIEN