Working with SFTP in .NET Core

SFTP operations using SSH.NET in .NET Core

The SSH File Transfer Protocol (also Secure File Transfer Protocol, or SFTP) is often called “Secure FTP”, but has nothing common with original FTP (ref. SFTP vs FTP). As a network protocol, SFTP provides file access, file transfer, and file management over a reliable data stream. We often employ SFTP to transfer files between two independent systems in different networks.

According to a dotnet GitHub issue (link), .NET Core doesn’t support native SFTP or SCP protocols. Thus we need to borrow an external SFTP client library. Among a list of SFTP client libraries, SSH.NET is free and works fine for most use cases. After several years without new releases, SSH.NET recently released a version 2020.0.0-beta1. This beta version adds support for .NET Standard 2.0, which cooperates well with the current .NET Core 3 framework. (Update: the latest library also works well with .NET 5, .NET 6.)

As stated in its repository, the documentation for SSH.NET currently is not complete and up-to-date. Fortunately, we can easily figure out usage based on the tests in Renci.SshNet.Tests. By searching and selectively reading the provided tests, I am able to create some frequently-used functions. In this post, I will show you some basic usage of SSH.NET library.

You can find the full solution in my GitHub repository. The code shows how to list remote files and download/upload/delete a remote file. In my repository, I have also created a Dockerfile to demonstrate that the code works on Linux.

Show me the code

First, we need to install the latest SSH.NET NuGet package to our project.

dotnet add package SSH.NET

Then we define the SFTP connection configurations. In this demo, we will use the username:password authentication.

SSH.NET also supports SSH keys (not shown in this demo). For demo purposes, we use a free online SFTP server “test.rebex.net”…