SFTP - SSH

SFTP (SSH File Transfer Protocol) is a network protocol that provides file access, file transfer, and file management over any reliable data stream. It was designed by the Internet Engineering Task Force (IETF) as an extension of the Secure Shell protocol (SSH) version 2.0 to provide secure file transfer capabilities.

This connector is available in the following products and regions:

Service Class Regions
Logic Apps Standard All Logic Apps regions and Integration Service Environments (ISEs)
Power Automate Standard All Power Automate regions except the following:
     -   US Government (GCC High)
     -   US Department of Defense (DoD)
Power Apps Standard All Power Apps regions except the following:
     -   US Government (GCC High)
     -   US Department of Defense (DoD)
Contact
Name Microsoft
URL Microsoft LogicApps Support
Microsoft Power Automate Support
Microsoft Power Apps Support
Connector Metadata
Publisher Microsoft

Connector how-to guide

This article describes the operations for the SFTP-SSH managed connector, which is available for Azure Logic Apps, Power Automate, and Power Apps. The SFTP built-in connector is available only for Standard logic app workflows in Azure Logic Apps. For more information, see Connect to an SFTP server using SSH in Azure Logic Apps and SFTP built-in connector reference for Azure Logic Apps.

Differences from the deprecated SFTP managed connector

Compared to the deprecated SFTP managed connector, the SFTP-SSH managed connector provides the following key capabilities:

  • Uses the SSH.NET library, which is an open-source Secure Shell (SSH) library that supports .NET.

  • Provides the Create folder action, which creates a folder at the specified path on the SFTP server.

  • Provides the Rename file action, which renames a file on the SFTP server.

  • Caches the connection to SFTP server for up to 1 hour. This capability improves performance and reduces how often the connector tries connecting to the server. To set the duration for this caching behavior, edit the ClientAliveInterval property in the SSH configuration on your SFTP server.

Authentication and permissions

  • When you create a connection to your SFTP server, you have to provide your SFTP server address, account credentials, an SSH private key, and the SSH private key password. If your platform supports uploading large files using chunking, you also need both read and write access for the root folder on your SFTP server.

  • The SFTP-SSH connector supports both private key authentication and password authentication. However, the SFTP-SSH connector supports only the following private key formats, key exchange algorithms, encryption algorithms, and fingerprints:

  • When you provide your SSH private key for your connection, don't manually enter or edit the key, which might cause the connection to fail. Instead, make sure that you copy the key from your SSH private key file, and paste that key into the connection information box.

    To correctly copy and paste your SSH private key, follow these steps.

    1. Open your SSH private key file in any text editor. These steps continue using Notepad as an example.

    2. In Notepad, from the Edit menu, select Select all. (Press Ctrl + A)

    3. From the Edit menu, select Copy.

    4. In the SFTP-SSH connection information box, paste the complete copied key into the SSH private key property, which supports multiple lines. Don't manually enter or edit the key.

    5. After you finish entering the connection details, select Create.

Convert PuTTY-based key to OpenSSH

The PuTTY format and OpenSSH format use different file name extensions. The PuTTY format uses the .ppk, or PuTTY Private Key, file name extension. The OpenSSH format uses the .pem, or Privacy Enhanced Mail, file name extension. If your private key is in PuTTY format, and you have to use OpenSSH format, first convert the key to the OpenSSH format by following these steps:

  • Unix-based OS

    1. If you don't have the PuTTY tools installed on your system, do that now, for example:

      sudo apt-get install -y putty

    2. Run the following command, which creates a file that you can use with the SFTP-SSH connector:

      puttygen <path-to-private-key-file-in-PuTTY-format> -O private-openssh -o <path-to-private-key-file-in-OpenSSH-format>

      For example

      puttygen /tmp/sftp/my-private-key-putty.ppk -O private-openssh -o /tmp/sftp/my-private-key-openssh.pem

  • Windows OS

    1. If you haven't done so already, download the latest PuTTY Generator (puttygen.exe) tool, and then open the tool.

    2. In the PuTTY Key Generator tool (puttygen.exe), under Actions, select Load.

    3. Browse to your private key file in PuTTY format, and select Open.

    4. From the Conversions menu, select Export OpenSSH key.

    5. Save the private key file with the .pem file name extension.

Find the MD5 fingerprint

The SFTP-SSH connector rejects a connection if both the SFTP server's fingerprint and expected fingerprint don't match. To get the MD5 fingerprint, which is a sequence with 16 pairs of hex digits delimited by colons, try the following options.

You have the key

The MD5 key is a 47-character string delimited by colons. To get the MD5 fingerprint when you have the key, you can use tools such as ssh-keygen.

For example, from a Bash prompt, enter the following command:

ssh-keygen -l -f id_rsa.pub -E md5

You don't have the key

To get an MD5 fingerprint when you don't have a key, you can use the latest Server and Protocol Information Dialog tool by WinSCP, or you can use the PuTTY Configuration tool instead:

  1. In the PuTTY Configuration tool (putty.exe), in the Category window, expand Connection > SSH > Host keys.

  2. Under Host key algorithm preference, open the Algorithm selection policy list, and check that RSA appears at the top.

  3. If RSA doesn't appear at the top, select RSA, and then select Up until RSA moves to the top.

  4. Connect to your SFTP server with PuTTY. After the connection is created, when the PUTTY security alert appears, select More info.

    Note

    If the security alert doesn't appear, try clearing the SshHostKeys entry. Open the Windows registry editor, and browse to the following entry:

    Computer\HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\SshHostKeys

  5. After the PuTTY: information about the server's host key box appears, find the MD5 fingerprint property, and copy the 47-character string value, which looks like the following example:

    **:**:**:**:**:**:**:**:**:**:**:**:**:**:**:**

Known issues and limitations with triggers

  • SFTP managed connector triggers might experience missing, incomplete, or delayed results.

    • Missing results

      SFTP triggers work by polling, or checking, the SFTP file system and looking for any files that changed since the last poll. SFTP managed connector triggers compare file versions using the file's last modified timestamp.

      If you create, add, or update file with a timestamp that's earlier than the currently tracked last modified timestamp, the SFTP managed connector trigger won't detect this file.

      So, if you use an external tool or client that creates, adds, or updates files on the SFTP server, make sure that you disable any feature in the tool or client that preserves a file's last modified timestamp.

      The following table lists some commonly used tools that preserve this timestamp and the steps to disable this feature:

      SFTP client Action
      WinSCP Go to Options > Preferences > Transfer > Edit > Preserve timestamp > Disable.
      FileZilla Go to Transfer > Preserve timestamps of transferred files > Disable.
    • Incomplete or delayed results

      When an SFTP trigger checks for a newly created, added, or updated file, the trigger also checks whether the file is complete. For example, a file might have changes in progress when the trigger checks the SFTP server. To avoid returning an incomplete file, the trigger notes the file's timestamp, but doesn't immediately return the file. Instead, the trigger returns the file only when the trigger checks the server again.

      Sometimes, this behavior might cause a delay that lasts as long as almost twice the trigger's polling interval. Due to this behavior, if you disable the SFTP trigger's Split On setting, the SFTP trigger might not return all files at the same time.

General known issues and limitations

  • The SFTP-SSH managed connector currently doesn't support the following SFTP servers:

    • FileMage Gateway
    • Globalscape
    • IBM DataPower
    • MessageWay
    • OpenText Secure MFT
    • OpenText GXS
    • SFTP for Azure Blob Storage
    • VShell Secure File Transfer Server
  • Use separate SFTP folders for file processing and uploading.

    Make sure to use separate folders on your SFTP server for the trigger to monitor files for processing and for storing uploaded files. Otherwise, the trigger won't fire and behaves unpredictably. For example, the trigger might skip a random number of files that need processing.

    This limitation means that you need a way to move files between those folders. If you encounter this problem, remove the files from the monitored folder, and use a different folder to store uploaded files.

  • The managed SFTP-SSH connector can create a limited number of connections to the SFTP server, based on the connection capacity in the Azure region where your app exists. For Azure Logic Apps, if this limit poses a problem in a Consumption logic app workflow, consider creating a Standard logic app workflow and use the SFTP built-in connector instead.

Chunking

  • In Azure Logic Apps and Power Automate, the following managed SFTP-SSH connector actions support chunking where an action can enable handling large files in smaller pieces. For more information about chunking in Azure Logic Apps, see [Handle large messages using chunking]](/azure/logic-apps/logic-apps-handle-large-messages).

    Action Chunking support Override chunk size support
    Copy file No Not applicable
    Create file Yes Yes
    Create folder Not applicable Not applicable
    Delete file Not applicable Not applicable
    Extract archive to folder Not applicable Not applicable
    Get file content Yes Yes
    Get file content using path Yes Yes
    Get file metadata Not applicable Not applicable
    Get file metadata using path Not applicable Not applicable
    List files in folder Not applicable Not applicable
    Rename file Not applicable Not applicable
    Update file No Not applicable

    SFTP-SSH actions that support chunking can handle files up to 1 GB, while SFTP-SSH actions that don't support chunking can handle files up to 50 MB. The default chunk size is 15 MB. However, this size can dynamically change, starting from 5 MB and gradually increasing to the 50 MB maximum. Dynamic sizing is based on factors such as network latency, server response time, and so on.

    Note

    For logic apps in an integration service environment (ISE), this connector's ISE-labeled version requires chunking to use the ISE message limits instead.

    You can override this adaptive behavior when you specify a constant chunk size to use instead. This size can range from 5 MB to 50 MB. For example, suppose you have a 45-MB file and a network that can that support that file size without latency. Adaptive chunking results in several calls, rather that one call. To reduce the number of calls, you can try setting a 50-MB chunk size. In different scenario, if your logic app workflow is timing out, for example, when using 15-MB chunks, you can try reducing the size to 5 MB.

    Chunk size is associated with a connection. This attribute means you can use the same connection for both actions that support chunking and actions that don't support chunking. In this case, the chunk size for actions that support chunking ranges from 5 MB to 50 MB.

    To override the default adaptive behavior that chunking uses on an SFTP-SSH action, you can specify a constant chunk size from 5 MB to 50 MB.

    1. On the designer, in the SFTP-SSH action's upper-right corner, select the ellipses button (...), and then select Settings.

    2. Under Content Transfer, in the Chunk size property, enter an integer value from 5 to 50.

    3. After you finish, select Done.

  • SFTP-SSH triggers don't support message chunking. When triggers request file content, they select only files that are 15 MB or smaller. To get files larger than 15 MB, follow this pattern instead:

    1. Use an SFTP-SSH trigger that returns only file properties. These triggers have names that include the description, (properties only).

    2. Follow the trigger with the SFTP-SSH Get file content action. This action reads the complete file and implicitly uses message chunking.

Troubleshooting

401 error: "401 Unauthorized"

This error might happen because you don't have the correct credentials or permissions. For more information, see Authentication and permissions.

404 error: "A reference was made to a file or folder which does not exist"

This error might happen when you use Create file action. When the action creates a file on your SFTP server, the action also automatically sends a call to your SFTP server to get the file's metadata.

If you immediately move the newly created file before the call can get the metadata, the file no longer exists at the expected location, and you get a 404 error message, A reference was made to a file or folder which does not exist.

If you can't avoid or delay moving the file, you can skip reading the file's metadata after file creation by following these steps:

  1. In the Create file action, open the Add new parameter list, select the Get all file metadata property, and set the value to No.

  2. If you need this file metadata later, you can use the Get file metadata action.

504 error: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" or "Request to the SFTP server has taken more than '00:00:30' seconds"

This error might happen when you can't successfully establish a connection with the SFTP server. There might be different reasons for this problem, so try these troubleshooting options:

  • The connection timeout is 20 seconds. Check that your SFTP server has good performance and intermediate devices, such as firewalls, aren't adding overhead.

  • Check whether your SFTP server puts a limit on the number of connections from each IP address. Any such limit hinders communication between the connector and the SFTP server. Make sure to remove this limit.

  • If you have a firewall set up, make sure that you add the managed connector IP addresses for your region to the approved list.

  • If the error happens intermittently, change the Retry policy setting on the SFTP-SSH action to a retry count higher than the default four retries.

  • To reduce connection establishment cost, in the SSH configuration for your SFTP server, increase the ClientAliveInterval property to around one hour.

  • Review the SFTP server log to check whether calls sent to your SFTP server arrive successfully, To get more information about the connectivity problem, you can also run a network trace on your firewall and your SFTP server.

General Limits

Name Value
Maximum number of megabytes being transferred to/from the connector within a bandwidth time interval (per connection) 1000
Bandwidth time interval (in miliseconds) 60000

Creating a connection

The connector supports the following authentication types:

Default Parameters for creating connection. All regions Not shareable

Default

Applicable: All regions

Parameters for creating connection.

This is not shareable connection. If the power app is shared with another user, another user will be prompted to create new connection explicitly.

Name Type Description Required
Host server address string Host server address True
User name string User name True
Password securestring Password
SSH private key securestring SSH private key (the content of the file should be provided entirely as is, in the multiline format)
SSH private key passphrase securestring SSH private key passphrase (if the private key is protected by a passphrase)
Port number int SFTP port number (example: 22)
Disable SSH host key validation bool Disable SSH host key validation? (True/False)
SSH host key finger-print string SSH host key finger-print
Root folder path string Root folder path.

Throttling Limits

Name Calls Renewal Period
API calls per connection15060 seconds

Actions

Copy file

This operation copies a file.

Create file

This operation uploads a file.

Create folder

This operation creates a new folder.

Delete file

This operation deletes a file.

Extract archive to folder

This operation extracts an archive file into a folder (example: .zip).

Get file content

This operation gets file contents using the file id.

Get file content using path

This operation gets file contents using the file path.

Get file metadata

This operation gets file metadata using the file id.

Get file metadata using path

This operation gets file metadata using the file path.

List files in folder

This operation gets files contained in a folder.

List files in root folder

This operation gets the files in the root folder.

Rename File

This operation renames a file.

Update file

This operation updates the file content.

Copy file

This operation copies a file.

Parameters

Name Key Required Type Description
Source file path
source True string

Path to the source file

Destination file path
destination True string

Path to the destination file, including file name

Overwrite?
overwrite boolean

Overwrites the destination file if set to 'true'

Get all file metadata
ReadFileMetadataFromServer boolean

Get all file metadata from the SFTP server after file creation is complete. If this is false, some metadata properties may not be returned such as last modified time, etc.

Returns

Blob metadata

Create file

This operation uploads a file.

Parameters

Name Key Required Type Description
Folder path
folderPath True string

Unique path of the folder

File name
name True string

Name of the file

File content
body True binary

Content of the file to create

Get all file metadata
ReadFileMetadataFromServer boolean

Get all file metadata from the SFTP server after file creation is complete. If this is false, some metadata properties may not be returned such as last modified time, etc.

Returns

Blob metadata

Create folder

This operation creates a new folder.

Parameters

Name Key Required Type Description
Folder
folderPath True string

Select a folder

Name
name True string

Name of the folder

Returns

Blob metadata

Delete file

This operation deletes a file.

Parameters

Name Key Required Type Description
File
id True string

Specify the file

Skip delete if file not found
SkipDeleteIfFileNotFoundOnServer boolean

Skips deletion if a file is not found without failing action.

Extract archive to folder

This operation extracts an archive file into a folder (example: .zip).

Parameters

Name Key Required Type Description
Source archive file path
source True string

Path to the archive file

Destination folder path
destination True string

Path to the destination folder

Overwrite?
overwrite boolean

Overwrites the destination files if set to 'true'

Returns

Get file content

This operation gets file contents using the file id.

Parameters

Name Key Required Type Description
File
id True string

Specify the file id

Infer Content Type
inferContentType boolean

Infer content-type based on extension

Returns

The content of the file.

File Content
binary

Get file content using path

This operation gets file contents using the file path.

Parameters

Name Key Required Type Description
File path
path True string

Unique path of the file

Infer Content Type
inferContentType boolean

Infer content-type based on extension

Returns

The content of the file.

File Content
binary

Get file metadata

This operation gets file metadata using the file id.

Parameters

Name Key Required Type Description
File
id True string

Specify the file id

Returns

Blob metadata

Get file metadata using path

This operation gets file metadata using the file path.

Parameters

Name Key Required Type Description
File path
path True string

Unique path of the file

Returns

Blob metadata

List files in folder

This operation gets files contained in a folder.

Parameters

Name Key Required Type Description
Folder
id True string

Specify the folder

Returns

List files in root folder

This operation gets the files in the root folder.

Returns

Rename File

This operation renames a file.

Parameters

Name Key Required Type Description
File
id True string

Select a file

New name
newName True string

New name for the file

Get all file metadata
ReadFileMetadataFromServer boolean

Get all file metadata from the SFTP server after file creation is complete. If this is false, some metadata properties may not be returned such as last modified time, etc.

Returns

Represents blob datasets metadata response

Update file

This operation updates the file content.

Parameters

Name Key Required Type Description
File
id True string

Specify the file

File content
body True binary

Content of the file to update

Get all file metadata
ReadFileMetadataFromServer boolean

Get all file metadata from the SFTP server after file creation is complete. If this is false, some metadata properties may not be returned such as last modified time, etc.

Returns

Blob metadata

Triggers

When a file is added or modified

This operation triggers a flow when a file is added or modified in a folder. The trigger will fetch both the file metadata as well as the content of the file. The trigger relies on the last modified time of a file. If a file is being created by a third-party client, the preservation of the last modified time should be disabled in the client. Files larger than 50 megabytes are skipped by the trigger. The trigger does not fire if a file is added/updated in a subfolder. If it is required to trigger on subfolders, multiple triggers should be created.

When files are added or modified (properties only)

This operation triggers a flow when a file is added or modified in a folder. This trigger will only fetch the file metadata. To get the file content, you can use the "Get file content" operation. The trigger relies on the last modified time of a file. If a file is being created by a third-party client, the preservation of the last modified time should be disabled in the client. The trigger does not fire if a file is added/updated in a subfolder. If it is required to trigger on subfolders, multiple triggers should be created.

When a file is added or modified

This operation triggers a flow when a file is added or modified in a folder. The trigger will fetch both the file metadata as well as the content of the file. The trigger relies on the last modified time of a file. If a file is being created by a third-party client, the preservation of the last modified time should be disabled in the client. Files larger than 50 megabytes are skipped by the trigger. The trigger does not fire if a file is added/updated in a subfolder. If it is required to trigger on subfolders, multiple triggers should be created.

Parameters

Name Key Required Type Description
Folder
folderId True string

Specify a folder

Include file content
includeFileContent boolean

If set to true, file content will also be retrieved along with the trigger response

Infer Content Type
inferContentType boolean

Infer content-type based on extension

Returns

The content of the file.

File Content
binary

When files are added or modified (properties only)

This operation triggers a flow when a file is added or modified in a folder. This trigger will only fetch the file metadata. To get the file content, you can use the "Get file content" operation. The trigger relies on the last modified time of a file. If a file is being created by a third-party client, the preservation of the last modified time should be disabled in the client. The trigger does not fire if a file is added/updated in a subfolder. If it is required to trigger on subfolders, multiple triggers should be created.

Parameters

Name Key Required Type Description
Folder
folderId True string

Select a folder

Number of files to return
maxFileCount integer

Number of files returned from the trigger (1-100)

Returns

Blob metadata

List of Files
BlobMetadata

Definitions

BlobMetadata

Blob metadata

Name Path Type Description
Id
Id string

The unique id of the file or folder.

Name
Name string

The name of the file or folder.

DisplayName
DisplayName string

The display name of the file or folder.

Path
Path string

The path of the file or folder.

LastModified
LastModified date-time

The date and time the file or folder was last modified.

Size
Size integer

The size of the file or folder.

MediaType
MediaType string

The media type of the file or folder.

IsFolder
IsFolder boolean

A boolean value (true, false) to indicate whether or not the blob is a folder.

ETag
ETag string

The etag of the file or folder.

FileLocator
FileLocator string

The filelocator of the file or folder.

BlobMetadataResponse

Represents blob datasets metadata response

Name Path Type Description
Id
Id string

The unique id of the file or folder.

Name
Name string

The name of the file or folder.

DisplayName
DisplayName string

The display name of the file or folder.

Path
Path string

The path of the file or folder.

LastModified
LastModified date-time

The date and time the file or folder was last modified.

Size
Size integer

The size of the file or folder.

MediaType
MediaType string

The media type of the file or folder.

IsFolder
IsFolder boolean

A boolean value (true, false) to indicate whether or not the blob is a folder.

ETag
ETag string

The etag of the file or folder.

FileLocator
FileLocator string

The filelocator of the file or folder.

binary

This is the basic data type 'binary'.