SSH host key fingerprint does not match pattern C# WinSCP

Question

I am trying to connect to an FTPS server using C# via WinSCP and I am getting this error:

SSH host key fingerprint ... does not match pattern ...

After tons of research, I believe is has something to do with the length of the key. The key I got from WinSCP when connected using its interface under "Server and protocol information" is xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx but the ones I saw in the example is shorter like this xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx

Can someone please help and offer me any pointer to resolve this would be greatly appreciated.

Here is my code

string winscpPath = "C:\\Program Files (x86)\\WinSCP\\WinSCP.exe";
string username = "User123";
string password = "abc1234";
string ftpSite = "192.168.5.110";
string localPath = "C:\\Users\\ttom\\Documents";
string remoteFTPDirectory = "/Usr/thisfolder";
string sshKey = "1b:68:10:80:77:c6:65:91:51:31:5t:65:1c:g6:13:20:39:g8:d8:6d";
Boolean winSCPLog = true;
string winSCPLogPath = "C:\\Users\\ttom\\Documents\\Visual Studio 2015\\Projects\\WebApplication1\\WebApplication1";

SessionOptions sessionOptions = new SessionOptions
{
    Protocol = Protocol.Sftp,
    HostName = ftpSite,
    UserName = username,
    Password = password,
    SshHostKeyFingerprint = sshKey
};

using (Session session = new Session())
{
    // WinSCP .NET assembly must be in GAC to be used with SSIS,
    // set path to WinSCP.exe explicitly, if using non-default path.
    session.ExecutablePath = winscpPath;
    session.DisableVersionCheck = true;

    if (winSCPLog)
    {
        session.SessionLogPath = @winSCPLogPath + @"ftplog.txt";
        session.DebugLogPath = @winSCPLogPath + @"debuglog.txt";
    }

    // Connect
    session.Timeout = new TimeSpan(0, 2, 0); // two minutes
    session.Open(sessionOptions);

    TransferOptions transferOptions = new TransferOptions();
    transferOptions.TransferMode = TransferMode.Binary;

    session.GetFiles(remoteFTPDirectory + "/" +
        "test.txt", localPath, false, transferOptions);
}

Martin Prikryl Martin Prikryl · Accepted Answer · 2016-01-28T06:58:34

You are connecting using SFTP (over SSH) in the code, but using FTPS (FTP over TLS/SSL) in GUI.

These are two completely different protocols.

Use Protocol = Protocol.Ftp and enable TLS/SSL using FtpSecure = FtpSecure.Explicit.

SessionOptions sessionOptions = new SessionOptions
{
    Protocol = Protocol.Ftp,
    FtpSecure = FtpSecure.Explicit,
    HostName = ftpSite,
    UserName = username,
    Password = password,
};

An equivalent of SshHostKeyFingerprint for FTPS is TlsHostCertificateFingerprint. But you need to use it only when the TLS/SSL certificate is not signed by a trusted authority (e.g. a self signed certificate).

The easiest is to have WinSCP GUI generate code for you.

SSH host key fingerprint does not match pattern C# WinSCP

4 Answers