Error: Server HMAC algorithm not found while connecting to SFTP server from consumption logic app

Question

While connecting to SFTP server from consumption logic app getting below error.

Server HMAC algorithm not found

Checked the documentation of correct it is using SSH.Net library. All the protocols mentioned are supported at SFTP side.

SFTP server is hosted in AWS and have security policies 2023-5 mentioned in the link.

https://docs.aws.amazon.com/transfer/latest/userguide/security-policies.html#security-policy-transfer-2023-05

{
  "status": 400,
  "message": "Server HMAC algorithm not found\r\nclientRequestId: xxxxxx-xxxx-45bf-bea4-xxxxxx",
  "error": {
    "message": "Server HMAC algorithm not found"
  },
  "source": "sftpwithssh-we.azconn-we-002.p.azurewebsites.net"
}

Answer 1

Hello Shashank, Welcome to MS Q&A

The error "Server HMAC algorithm not found" indicates that the HMAC algorithm used by the SFTP server is not supported by the SSH.Net library used by Azure Logic Apps. This can happen if the SFTP server is using a newer or less common HMAC algorithm that is not recognized by the library.

To resolve this issue, you can try the following steps:

Check Supported Algorithms: Ensure that the HMAC algorithms used by your SFTP server are supported by the SSH.Net library. The supported algorithms typically include hmac-md5, hmac-sha1, hmac-sha2-256, and hmac-sha2-512.

Update Security Policies: If possible, update the security policies on your SFTP server to use one of the supported HMAC algorithms. You can refer to the AWS documentation for the security policies and ensure that the algorithms match those supported by SSH.Net.

Update SSH.Net Library: If you have control over the Azure Logic App's environment, consider updating the SSH.Net library to the latest version, as it may include support for additional HMAC algorithms.

Custom Connector: If the above steps do not resolve the issue, you may need to create a custom connector in Azure Logic Apps that uses a different library or method to connect to the SFTP server.

Since the documentation retrieval failed, you may need to manually verify the supported HMAC algorithms in the SSH.Net library and compare them with the algorithms used by your SFTP server.

Please check and let us know if any questions

Kindly accept answer if it helps

Thanks
Deepanshu

Answer 2

Hi,
To handle this case I have used Azure function and used SSH.net library latest version. In the latest version of SSH.Net package you won't face this issue.

I think Logic app managed connectors are using older version might be this is the reason for this issue.