WinSCP C# Example

using System;
using WinSCP;
 
class Example
{
    public static int Main()
    {
        try
        {
            // Setup session options
            SessionOptions sessionOptions = new SessionOptions
            {
                Protocol = Protocol.Sftp,
                HostName = "example.com",
                UserName = "user",
                Password = "mypassword",
                SshHostKeyFingerprint = "ssh-rsa 2048 xxxxxxxxxxx...="
            };
 
            using (Session session = new Session())
            {
                // Connect
                session.Open(sessionOptions);
 
                // Upload files
                TransferOptions transferOptions = new TransferOptions();
                transferOptions.TransferMode = TransferMode.Binary;
 
                TransferOperationResult transferResult;
                transferResult =
                    session.PutFiles(@"d:\toupload\*", "/home/user/", false, transferOptions);
 
                // Throw on any error
                transferResult.Check();
 
                // Print results
                foreach (TransferEventArgs transfer in transferResult.Transfers)
                {
                    Console.WriteLine("Upload of {0} succeeded", transfer.FileName);
                }
            }
 
            return 0;
        }
        catch (Exception e)
        {
            Console.WriteLine("Error: {0}", e);
            return 1;
        }
    }
}

        public string[] GetFileList()
        {
            List<string> list = new List<string>();

            try
            {
                // Create a new Sftp instance.
                SessionOptions sessionOptions = new SessionOptions
                {
                    Protocol = Protocol.Sftp,
                    HostName = ServerAddress,
                    UserName = OutUser,
                    Password = OutPwd,
                    //SshHostKeyFingerprint = "ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx..."
                    GiveUpSecurityAndAcceptAnySshHostKey = true,
                };

                using (Session session = new Session())
                {
                    // Connect
                    session.Open(sessionOptions);

                    // Enumerate files and directories to download
                    list = session.EnumerateRemoteFiles(OutDirectory, null, EnumerationOptions.None)
                            .Select(f => f.Name).ToList();

                }

                return list.ToArray();
            }
            catch (Exception ex)
            {
                log.ErrorFormat("GetFtpFileList: {0}", ex.Message);
                return null;
            }
        }

Note: If ppk is required by destination FTP site, make sure the ppk is loaded into Pageant first. Else authentication will fail when the .NET app tries to connect to the FTP site, even if “GiveUpSecurityAndAcceptAnySshHostKey = true” is set.

Sources:

https://winscp.net/eng/docs/library_examples