SMB 3 Implementation in .net core

Aniesha Razdan 40

There isn't any library available to implement network file sharing using SMB3 protocol in .net core. The existing SMBLibrary only supports SMB1 and SMB2. Which library to use for SMB3 implementation?

Jiale Xue - MSFT 47,501 Reputation points Microsoft Vendor

2024-08-21T02:35:02.83+00:00

Hi @Aniesha Razdan , Welcome to Microsoft Q&A,

Microsoft currently does not directly provide a library that supports the SMB3 protocol for .NET Core. The implementation of the SMB (Server Message Block) protocol is more integrated into the Windows operating system itself, rather than as a separate .NET library. Through the APIs and functions provided by Windows, .NET applications can indirectly use the SMB3 protocol.

Use P/Invoke to call the Windows native API to implement SMB3 protocol related functions.

https://learn.microsoft.com/en-us/windows/win32/api/lmshare/

If your app is running on a system like Windows Server or Windows 10, SMB3 is already supported by the operating system, and you can use SMB3 by configuring Windows file shares without having to implement the protocol directly in .NET Core.

Best Regards,

Jiale

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Aniesha Razdan 40 Reputation points

2024-08-21T06:14:05.7633333+00:00

Hi @Jiale Xue - MSFT

Can this solution be used in azure function or app service?
Jiale Xue - MSFT 47,501 Reputation points Microsoft Vendor

2024-08-21T06:24:35.6766667+00:00

Azure Functions and Azure App Services often run in restricted environments that do not allow direct access to the underlying operating system's APIs. P/Invoke relies on access to the underlying operating system, so using native Windows APIs in these environments may be limited or not supported at all.

Azure File Storage natively supports the SMB3 protocol and is the most direct alternative. You can interact with Azure File Storage in a function or app service through the Azure SDK without calling the local API.

To consult Azure-related questions, you need to add the corresponding Azure tag, and someone will be involved in your question.
Aniesha Razdan 40 Reputation points

2024-08-21T06:40:38.06+00:00

I need to place a file in azure path which is present in an on-prem environment using .net core api. I also need to pass credentials to authenticate while accessing the azure path for which i needed to use SMB3 protocol. Can Azure File Storage be used in a function or app service through the Azure SDK to achieve this?
Aniesha Razdan 40 Reputation points

2024-08-21T12:04:36.6866667+00:00

@Jiale Xue - MSFT, to use P/Invoke to call the Windows native API to implement SMB3 protocol related functions, what would be the library that is to be imported and its respective function to be used to implement smb functionality?
Nehruji R 8,156 Reputation points Microsoft Vendor

2024-08-27T12:41:29.31+00:00

Hi, we hope the below information helped if yes please accept the answer, else please let us know if you have any further queries.
Nehruji R 8,156 Reputation points Microsoft Vendor

2024-09-02T06:28:48.05+00:00

Hi, we hope the below answer helped if yes please accept the answer else, please let us know if you have any further queries. I’m happy to assist you further.
荒井　元成 0 Reputation points

2024-12-03T06:50:59.1766667+00:00

In Windows you use the OS functions, but how do you do this in Linux?

Accepted answer

Bruce (SqlWork.com) 67,921 Reputation points

2024-08-21T16:10:10.4533333+00:00

azure function and apps don't support on premise SMB because the ports are blocked in the hosting sandbox.

You will need to use an azure virtual machine and configure point to point access:

https://learn.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-howto-point-to-site-resource-manager-portal

or an azure logic app using on-premise data connectors:

https://learn.microsoft.com/en-us/azure/connectors/file-system?tabs=consumption
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Nehruji R 8,156 Reputation points Microsoft Vendor

2024-08-22T06:39:31.38+00:00

Hello Aniesha Razdan,

Greetings! Welcome to Microsoft Q&A Platform.

P/Invoke is a technology that allows you to access structs, callbacks, and functions in unmanaged libraries from your managed code. Most of the P/Invoke API is contained in two namespaces: System and System.Runtime.InteropServices. Using these two namespaces give you the tools to describe how you want to communicate with the native component and to use P/Invoke for implementing SMB3 protocol-related functions, you would typically import the Mpr.dll library, which contains the necessary functions for network resource management, including SMB.

refer - https://learn.microsoft.com/en-us/dotnet/standard/native-interop/pinvoke, https://github.com/dotnet/pinvoke,https://learn.microsoft.com/en-us/dotnet/api/overview/azure/storage.files.shares-readme?view=azure-dotnet for more details.

You can mount the file share on your local machine by using the SMB 3.0 protocol, or you can use tools like Storage Explorer to access files in your file share. From your application, you can use storage client libraries, REST APIs, PowerShell, or Azure CLI to access your files in the Azure file share.

More information here: https://learn.microsoft.com/en-us/azure/storage/files/storage-files-faq

Hope the above information helps! Please let us know if you have any further queries. I’m happy to assist you further.

Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
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Aniesha Razdan 40 Reputation points

2024-08-22T15:21:15.0966667+00:00

Hi Nehruji R,

for the same implementation, i tried using azcopy but couldn't find any way to pass smb credentials for authentication to access the shared folder, an azcopy command. Is there any command where along with the destination folder path we can pass credentials to access that folder?

Bruce (SqlWork.com) 67,921 Reputation points

2024-08-26T02:29:45.7166667+00:00

Azcopy runs on your local network. On Linux/Mac it uses Kerberos to access the file share, and only one Kerberos account can be active at a time. On a Mac use ticket viewer, on Linux use kinit. On windows you can use the runas command to control the access account.

You might want on-prem webserver that allowed azure access to a on-prem file share.
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SMB 3 Implementation in .net core

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