An FTP secure client library for C#

The code is working fine when doing common FTP.
I am using Port 21, and the connection fails when getSslStream. With FilieZilla it works.
The Remote needs explicit FTP over SSL ist this the Problem? How to do?

C#

I am using yahoo small business server  ftp 
it work correctly connection ,username and pass , check is passing

then it stop in  ftp.uploadSecure("c://test.txt", false);

it hang out on second time when calling 
_sslStream.AuthenticateAsClient(
                 remoteHost,
                 null,
                System.Security.Authentication.SslProtocols.Ssl2 | System.Security.Authentication.SslProtocols.Tls,
                true);

??? any idea ??

I am also facing same issue , do u got any solution ?

I am getting some exception
see
below
System.Net.Sockets.SocketException was unhandled
HResult=-2147467259
Message=The requested name is valid, but no data of the requested type was found
Source=System
ErrorCode=11004
NativeErrorCode=11004
StackTrace:
at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6)
at System.Net.Dns.Resolve(String hostName)
at FTP_DLL.FTPFactory.loginWithoutUser() in c:cp\FTPSecure\FTPTest\FTP.cs:line 259
at ConsoleApplication2.Program.Main(String[] args) in D:\SampleWork\ConsoleApplication2\ConsoleApplication2\Program.cs:line 21
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:

I applaud the author Kadaoui El Mehdi for taking the initiative to learn FTP protocol and implement a client. An FTP client library is definitely not an easy task.

Unfortunately, I could not get the library to work in FTPS explicit mode with a Microsoft FTP server. After some tweaking, I managed to get it to log in, but I could not get a directory listing. Since I didn't have the time or desire to learn the nuts and bolts of FTP, I had to try something else. I wound up using FtpWebRequest class which worked easily, but obviously I had to accept the "stateless" model that it offers.

One of the things I noticed about the code in FTP_DLL.FTPFactory is that the calls to Socket.Receive use the return value incorrectly to test for "End Of File". The code should test for 0 bytes returned, instead of a less than full buffer. The Socket will return *up to* BLOCK_SIZE, but it doesn't have to fill the entire buffer. I have seen very rare instances where Socket.Receive returned a buffer that was less than full and it was not the end of the file. The effect on the user is that once in a while, only the first portion of the file will be downloaded.

It works well .... may be you should understand the protocol and adapt to your server !!!!

is System.Net.Ftp[^]. I could not, for the life of me get this one to work with my TLS FTP server, I spent several hours trying and making the changes suggested in the comments and so on with no luck.

I tried System.Net.Ftp, which is also available on the NuGet package manager that comes in (at least) VS2013. Not sure about the other versions of VS. Anyway, that library worked great on the first try. Highly recommended, and it might save you guys some time of googling.

I´m trying to connect to a remote ftp server that require SSL connection under 990 door (implicit). I can do it without error under FileZilla but when i try to run the sample application with de code above, it is freezing after the ftp.login() method.

Code:

C#

FTPFactory ftp = new FTPFactory();
ftp.setDebug(true);
ftp.setRemoteHost(Settings.Default.TargetFtpSource);

//Connect to SSL Port (990)
ftp.setRemotePort(990);
ftp.setRemoteUser(Settings.Default.TargetFtpSecureUser);
ftp.setRemotePass(Settings.Default.TargetFtpSecurePass);
ftp.login();

app.config is properly setted.

Tks
Léo

Hi,
I am getting the below error
"Index was outside the bounds of the array."
in the readline() method
kindly help me it is urgent
host: 123.252.255.10
port: 22

C#

private string readLine()
      {
          while (true)
          {
              if (useStream)
                  bytes = stream.Read(buffer, buffer.Length, 0);
              else
                  bytes = clientSocket.Receive(buffer, buffer.Length, 0); 



              mes += ASCII.GetString(buffer, 0, bytes);
//===> message received is "SSH-2.0-OpenSSH_4.3"
              if (bytes &amp;lt; buffer.Length)
              {
                  break;
              }
          }
          char[] seperator = { &amp;#39;\n&amp;#39; };
          string[] mess = mes.Split(seperator);
          if (mes.Length &amp;gt; 2)
          {
              mes = mess[mess.Length - 2]; // ========== this is where i got error
          }&lt;/pre&gt;</pre>

I have the FTP class in my test project, but the authors implementation example just doesn't work as is...or at least not for me.

If anyone has a (working) basic example of using his class to connect to a SFTP server, I'd love to see it.

Thanks,

Barry

When, I am running the program, i am getting this error at loginwithoutuser function

base {System.Runtime.InteropServices.ExternalException} = {"An unknown, invalid, or unsupported option or level was specified in a getsockopt or setsockopt call"}

Hi,

I am new to this programming lanugauge, and cannot run the program as it needs and exe to execute.

Can someone share how I can do that..

Thanks

Mehdi,
Thank you. This program works great on my system connecting to FTP server(FTPS).

But on the client location, we need to connect to FTP server through the proxy. FileZilla client is able to connect to FTP server through the proxy settings.
Here in this program how to set these configuration work through the proxy.

Regards,
Killi

I downloaded the code and analyzed all of it. All of the SslStream sslStream = new SslStream(client.GetStream(), false); code is commented out. Is this still secure if I use this code?

Hi,

Thank you very much for the code. However, dir is not working using secure ftp. Any ideas?

Thanks,
Deb

The IBM FTP server I was using this class to access was freezing when trying to upload or download files. It froze on the _sslStream.AuthenticateAsClient function. The issue turned out to be the sequence of commands sent to the server. On the IBM FTP server you have to send the RETR/STOR commands first thing after creating the data transfer socket before you call the function to create the secure stream. I've edited the class a bit, but here are the revised upload and download functions I use that work with the IBM FTP server:

NOTE: The functionality to resume has been removed because our server doesn't support it. Also, you may notice the outDelegate. This is the function used to output. You can set it to any function that returns void and takes a string (Ex: Console.WriteLine).

C#

/// <summary>
/// Upload a file to the server
/// </summary>
/// <param name="fileName">The file name (including path) of the local file to upload</param>
/// <returns>True if successful, False otherwise</returns>
public bool Upload(string fileName)
{
    // If we aren't logged in already
    if (!loggedIn)
    {
        Login(); // Login
    }

    // Create the data socket and attempt to connect
    Socket cSocket = createDataSocket();
    isData = true;

    if (outDelegate != null)
    {
        outDelegate("Data Socket Connected: " + cSocket.Connected.ToString());
        if (appendNewLines)
            outDelegate("\n");
    }

    // Send the store command to the server
    sendCommand("STOR " + Path.GetFileName(fileName));

    if (!(retValue == 125 || retValue == 150))
    {
        if (outDelegate != null)
        {
            outDelegate("Error: Bad response from server during upload: " + reply);
            if (appendNewLines)
                outDelegate("\n");
        }
        return false;
    }

    // If we were able to secure the stream
    if (getSslStream(cSocket))
    {
        // Id the data socket is connected
        if (cSocket.Connected)
        {
            byte[] bufferFile = null;
            try
            {
                // Open the local file for reading
                FileStream input = File.OpenRead(fileName);
                if (outDelegate != null)
                {
                    outDelegate("Uploading file " + fileName + " to " + remoteDir);
                    if (appendNewLines)
                        outDelegate("\n");
                }

                while (true)
                {
                    bufferFile = new byte[BLOCK_SIZE];

                    int bytes = input.Read(bufferFile, 0, bufferFile.Length); // Fill the buffer with the file
                    dataStream.Write(bufferFile, 0, bufferFile.Length); // Write the buffer to the server using the secure stream

                    // If we read less bytes than the file had left, we reached the end of the file
                    if (bytes < bufferFile.Length)
                    {
                        break;
                    }
                }

                // Close the local file
                input.Close();

                if (outDelegate != null)
                {
                    outDelegate("File successfully uploaded");
                    if (appendNewLines)
                        outDelegate("\n");
                }
            }
            catch (Exception ex)
            {
                if (outDelegate != null)
                {
                    outDelegate("Error uploading file: " + ex.Message);
                    if (appendNewLines)
                        outDelegate("\n");
                }
                return false;
            }
        }

        // Close the secure stream
        dataStream.Close();
    }

    // If the socket is still connected, close it
    if (cSocket.Connected)
    {
        cSocket.Close();
    }

    // Read and check the reply
    readReply();
    if (!(retValue == 226 || retValue == 250))
    {
        if (outDelegate != null)
        {
            outDelegate("Error: Bad response from server during upload: " + reply);
            if (appendNewLines)
                outDelegate("\n");
        }
        return false;
    }

    isData = false;
    return true;
}

/// <summary>
/// Downloads a file from the server
/// </summary>
/// <param name="remFileName">Filename of the file on the server</param>
/// <param name="locFileName">Filename (with path) of the local file</param>
/// <returns>True if successful, False otherwise</returns>
public bool Download(string remFileName, string locFileName = null)
{
    // If we aren't logged in, do so now
    if (!loggedIn)
    {
        Login();
    }

    isData = true;

    // If the local file isn't set, default it to be the same name as the server's file name
    if (locFileName == null || locFileName.Equals(""))
    {
        locFileName = remFileName;
    }

    try
    {
        // Create or open the local file for writing
        FileStream output = new FileStream(locFileName, FileMode.OpenOrCreate, FileAccess.Write);

        // Create the data socket
        Socket cSocket = createDataSocket();

        // Send the retrieve command to the server
        sendCommand("RETR " + remFileName);

        if (!(retValue == 150 || retValue == 125))
        {
            if (outDelegate != null)
            {
                outDelegate("Error: Bad response from server during download: " + reply);
                if (appendNewLines)
                    outDelegate("\n");
            }
            return false;
        }

        // Secure the stream
        this.getSslStream(cSocket);

        if (cSocket.Connected)
        {
            if (outDelegate != null)
            {
                outDelegate("Downloading file " + remFileName + " from " + remoteHost);
                if (appendNewLines)
                    outDelegate("\n");
            }

            byte[] downBuffer = new byte[1024];
            int len;
            // Read the file from the server and write it to the local file
            while ((len = dataStream.Read(downBuffer, 0, downBuffer.Length)) > 0)
            {
                output.Write(downBuffer, 0, len);
            }

            dataStream.Close();
        }

        // Close everything
        output.Close();
        if (cSocket.Connected)
        {
            cSocket.Close();
        }

        // Read the reply
        readReply();
        if (!(retValue == 226 || retValue == 250))
        {
            if (outDelegate != null)
            {
                outDelegate("Error: Bad response from server during download: " + reply);
                if (appendNewLines)
                    outDelegate("\n");
            }
            return false;
        }
    }
    catch (Exception ex)
    {
        if (outDelegate != null)
        {
            outDelegate("Error downloading file: " + ex.Message);
            if (appendNewLines)
                outDelegate("\n");
        }
        return false;
    }

    if (outDelegate != null)
    {
        outDelegate("Download Complete");
        if (appendNewLines)
            outDelegate("\n");
    }

    isData = false;
    return true;
}

Appreciate the new functions, but you change of lot of external dependencies (function names/prototypes, variables, etc) and introduce new ones with no explanation (isData? remoteDir? dataStream? ). Can you post the whole new class you made?

Thanks!

I use the code successfully until it reaches for the function of readline where it throws an exception: Index and length must refer to a location within the string.\r\nParameter name: length
Please help, I ve been with that error for a week.

My remote site doesn't have anything on port 990, only on ports 21, 22, and 111.

I need to do a secure file download.

Using your sample, I get hung up doing the
SetRemotePort(990);

I've tried to do other things to download a file, but I was not successful.

I know the site's name, a valid username and password, and the file's pathname that I want to download. I don't know the steps to go through to get the file.

Thanks in advance.

You just need to use the correct port. I use port 21 with most servers, but the server determines the allowable port usage.

There are a few standards - FTPeS ( FTP over explicit SSL or TSL ) is preferred and generally uses the standard port 21. Implicit / non-negotiated FTPS using a standard port of 990.

SFTP or FTP over SSH / port 22 is less desirable. It really depends on the server requirements if you accessing as a client application.

The actual standards are quite technical with many variations and I am not trying to recite them but just give you a level to support your need.

A big difference is that SFTP only uses one stream, whereas FTPS, like FTP, uses at least two:

a control stream, where the commands are issued
another stream for each data transfer

If you are unsure, it's easy to use FileZilla to connect and observer the log, so you'll see the command activity. And you can test connectability of your port, credentials, etc. (e.g., I doubt you'll connect to port 990 but I can't be certain with what you've posted). With FTPeS, you'll see a "AUTH SSL", "AUTH TLS" or similar command in the stream. With Implicit (FTPS), you'll not see it.

Thank you very form providing wonderful help to handle sslStream security in out internal FTP Application.

I have some problem through this dll, I am able to connect secure FTP host, however unable to upload or download the files from the site, could you please help me.

Application use hung in sslStream.AunthenticationAsClient(...)

Regard
JACOB.

I had this problem as well. I solved it by creating the data socket, sending the STOR command first, then trying to create the secure stream that is used to upload the file. His class creates the data socket, tries to secure the stream (which hangs on the IBM FTP server I'm accessing) then sends the STOR command.

Hi! Can you please provide an example?
Did you mean call to SendCommand right after clientSocket.Connect?:

C#

clientSocket.Connect(ep);
SendCommand("STOR");

?

Hi,

I'm trying to upload a file but nothing happens.
I did exactly what you recommended on your article...

Anybody could help me?

Thank you

Here is the code

FTPFactory ftp = new FTPFactory();
ftp.setDebug(true);
ftp.setRemoteHost("Ftp://207.107.13.147/vp4603_casas/Admin/Datapacks/");
ftp.setRemotePort(22);
ftp.loginWithoutUser();
string cmd = "AUTH SSL";
ftp.sendCommand(cmd);

ftp.getSslStream();
ftp.setUseStream(true);

ftp.setRemoteUser("*****");
ftp.setRemotePass("******");

ftp.login();

ftp.setBinaryMode(false);
ftp.uploadSecure(@"C:\teste.exe", false);

ftp.close();

I had this problem as well. I solved it by creating the data socket, sending the STOR command first, then trying to create the secure stream that is used to upload the file. His class creates the data socket, tries to secure the stream (which hangs on the IBM FTP server I'm accessing) then sends the STOR command.

An FTP secure client library for C#

Introduction

SSL Stream?

Using the Code

1. Pre-Authenticate

2. Create SSL Stream

3. Upload File

Points of Interest

License

Comments and Discussions