Hello

I think we are one step forward:

After long trials: I have noticed following 2 points:

1)****************************************************************************
Just When I set following security parameters: (of course before creating client object)

ComManagement.Instance.Configuration.InstantiationParameters.OverrideDefaultSecurity = false;
ComManagement.Instance.Configuration.SecurityParameters.UseCustomSecurity = false;

I still get "Acces Denied" for browsing servers. but when I tried 1) client.BrowseBranches(ipaddress, "OPC.IwSCP.1" ,"") by writing the OPC Server name manualy
and 2) client.ReadMultipleItems(...) I can browse the branches and read also the values of the tags without problem !!!

That means: I have just problem on browsing the servers. I thought, when I get "Acces Denied" at this step I would get it also in browsing branches and reading items.
But as said with the above setted two security parameters browsing branches and reading items is working. But why not the browsing?

2)*****************************************************************************
After this observations I implemented the settings and the code in my real project (ASP NET Core Blazor Server Side with .NET7) which is on the same server like the console test app. In this case of course I can still not browse servers but when trying client.BrowseBranches(ipaddress, "OPC.IwSCP.1" ,"") this time I get following Error:

The COM server does not support the interface 'OpcRcw.Da.IOPCServer'.

This problem could be caused by:
- incorrectly installed proxy/stubs.
- problems with the DCOM security settings.
- a personal firewall (sometimes activated by default).

My code is

public void MTX_Connect()
{
ComManagement.Instance.Configuration.InstantiationParameters.OverrideDefaultSecurity = false;
ComManagement.Instance.Configuration.SecurityParameters.UseCustomSecurity = false;
Browse_Servers();
Browse_nodes();

}

public void Browse_Servers()
{
var client = new EasyDAClient();
ServerElementCollection serverElements;
try
{
serverElements = client.BrowseServers(IPAdress);
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
return;
}

foreach (ServerElement serverElement in serverElements)
{
Console.WriteLine($"ServerElements(\"{serverElement.ClsidString}\").ProgId: {serverElement.ProgId}");
using (StreamWriter sw = File.AppendText(CommonClass.error_path))
{
sw.WriteLine($"ServerElements(\"{serverElement.ClsidString}\").ProgId: {serverElement.ProgId}" + " " + Convert.ToString(DateTime.Now));

}
}
}

public void Browse_nodes()
{
// Instantiate the client object.
var client = new EasyDAClient();
DANodeElementCollection branchElements;
try
{
branchElements = client.BrowseBranches("10.92.120.174", "OPC.IwSCP.1", "");
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
return;
}

foreach (DANodeElement branchElement in branchElements)
{
Console.WriteLine($"BranchElements(\"{branchElement.Name}\").HasChildren: {branchElement.HasChildren}");
}

}

Hello

My target is to find a solution for this issue this week, so I will give my full capacity for this issue.
To your question, what is logged in the eventviewer: If I run my minimized console app with OPCLabs 5.62, I get just following info messages in the appl. log:

1) COM security initialization (process "ConsoleApp1" Id 13056, application domain "ConsoleApp1.exe" Id 1) for requestor 'ComSecurityInitializingEasyDAClient' succeeded; the initialization object was: (Default).
Made system call: yes, current thread name: "", from thread pool: no, apartment state: MTA.

2) COM instantiation parameters (process "ConsoleApp1" Id 13056, application domain "ConsoleApp1.exe" Id 1) are: OverrideDefaultSecurity=False.

Today I will add an algoritm into my code for adjusting all the relevant security parameters, programaticaly.
That means for each combination of the rel. parameters it will trigger o "browse server" automatically.

Before doing that I wanted to be sure: What security parameter should I add additionaly to the known 4 parameters for this test?

ComManagement.Instance.Configuration.InstantiationParameters.OverrideDefaultSecurity
ComManagement.Instance.Configuration.SecurityParameters.UseCustomSecurity
ComManagement.Instance.Configuration.SecurityParameters.TurnOffCallSecurity
ComManagement.Instance.Configuration.SecurityParameters.AllowImpersonateClient

Thank you for the links, I have read all of them.
I have nearly tried all of the combinations of following security parameters in 5.71,without succes. Always get Access is denied.
Is the order of the parameters critical? Or where exactly I should place them?

In 5.62, still I can browse and read data from the same opc.da server without setting any parameter.
Isn't there any formula of the security parameters to set, in order to achieve the state of 5.62?
I would give up long ago if with 5.62 I couldn't connect.

There is still something missing but what

ComManagement.Instance.Configuration.InstantiationParameters.OverrideDefaultSecurity = false; //allways false
ComManagement.Instance.Configuration.SecurityParameters.UseCustomSecurity = false; // true-false
ComManagement.Instance.Configuration.SecurityParameters.TurnOffCallSecurity = true; // true-false
ComManagement.Instance.Configuration.SecurityParameters.AllowImpersonateClient = true; // true-false
ComInstantiationParameters.Default.TurnOffActivationSecurity = // true-false

var client = new EasyDAClient();

//client.InstanceParameters.EnableNetApiClient = false;
ServerElementCollection serverElements;


try
{
Console.WriteLine("Halllooooooo");
serverElements = client.BrowseServers("10.92.120.174");
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
Console.ReadLine();
return;
}

foreach (ServerElement serverElement in serverElements)
{
Console.WriteLine($"ServerElements(\"{serverElement.ClsidString}\").ProgId: {serverElement.ProgId}");

}
Console.ReadLine();

Hello

I have used Quick OPC V5.62 without problem. I could connect to machine A 's OPC DA server without problem. (Without setting any security parameter)
I had to upgrade my .NET to .NET7 so I have updated Quick OPC to the latest version V5.71.
But then I got with the same code, on the same server , for the same machine the Error: "Acces Denied" while browsing the OPC DA servers.
As you see in the code below I have tried to set some security parameters with different combinations, but without succes.

I could reproduce the problem with a minimum .NET framework console app like this: (This is the complete code) NetFramework 4.7.2
For testing I run one console application with 5.62 and the other with 5.71 on the same server under the same conditions. (Visual Studio 2022 netframework 4.7.2, Debug mode)

With 5.62 I can browse the OPC DA servers without problem:
ServerElements("9cc7e5b1-dfa5-11d8-983b-000102df7c07").ProgId: Marposs.OPCServerDA.1
ServerElements("108fb1cf-f509-4d86-b1da-54bf1dd67a8d").ProgId: OPC.IwSCP.1
ServerElements("cd049e4b-67fb-4673-bf09-8d47896e3d09").ProgId: Studio.Scada.OPC
ServerElements("193b9f48-1d59-477b-933f-391346163677").ProgId: IndraLogic.OPC.02

With 5.71 I get Acces Denied Error
*** Failure: Access is denied.
+ COM security initialization object: (Default).
+ COM instantiation parameters: (Default).
+ The machine name was '10.92.120.174'.
+ Execution details: HasNativeClient=True, HasNetApiClient=True.
+ The client method called (or event/callback invoked) was 'BrowseServers'.

Is it possible that on V5.71(different to 5.62) some security parameters are set in default, so that I have to change them?
I think there must be something different in V5.71 compared to V5.62.

namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{

//These three lines I have added for 5.71 after I got "Acces Denied". With all possible combinations, still not worked
//ComManagement.Instance.Configuration.SecurityParameters.UseCustomSecurity = false;
//ComManagement.Instance.Configuration.SecurityParameters.TurnOffCallSecurity = true;
//ComInstantiationParameters.Default.TurnOffActivationSecurity = true;

var client = new EasyDAClient();
ServerElementCollection serverElements;
try
{
Console.WriteLine("Halllooooooo");
serverElements = client.BrowseServers(ipadress);
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
Console.ReadLine();
return;
}

foreach (ServerElement serverElement in serverElements)
{
Console.WriteLine($"ServerElements(\"{serverElement.ClsidString}\").ProgId: {serverElement.ProgId}");

}
Console.ReadLine();

}

}
}