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An FTP secure client library for C#

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10 Dec 2008CPOL2 min read 490K   15.8K   135   106
How to implement an FTP secure connection with an SSL stream class.

Introduction

The purpose of this article is to create a C # FTP client in Secure mode, so if you don’t have much knowledge of FTPS, I advise you to take a look at this: FTPS.

In the .NET Framework, to upload a file in FTPS mode, we generally use the FtpWebRequest class, but you can not send commands with « quote » arguments, and even if you search on the web, you will not find a concrete example of a secured C# FTP client.

It’s for those reasons I decided to create this article.

SSL Stream?

To send a socket in Secure Socket Layer (SSL) mode, we use the class System.Net.Security.SslStream.

Provides a stream used for client-server communication that uses the Secure Socket Layer (SSL) security protocol to authenticate the server and optionally the client”.

For more information, refer to MSDN.

Using the Code

1. Pre-Authenticate

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

//Connect to SSL Port (990)
ftp.setRemotePort(990);
ftp.loginWithoutUser();

//Send "AUTH SSL" Command
string cmd = "AUTH SSL";
ftp.sendCommand(cmd);

Before connecting to the FTP server in SSL mode, you have to define the 990 SSL port and send the « AUTH SSL » command authentication using SSL.

WelcomeFTPSecure.JPG

2. Create SSL Stream

C#
//Create SSL Stream
ftp.getSslStream();
ftp.setUseStream(true);
//Login to FTP Secure
ftp.setRemoteUser(Settings.Default.TargetFtpSecureUser);
ftp.setRemotePass(Settings.Default.TargetFtpSecurePass);
ftp.login();

ftp.getSslStream() creates an SSL stream from client socket which will be used for exchange between the client and the server FTPS. Then, you have to enter a login and password to authenticate on the FTPS server.

Note: if the SSL stream is well established, then I display all the information about the server certificate.

CertificatInfos.JPG

3. Upload File

C#
//Set ASCII Mode
ftp.setBinaryMode(false);

//Send Arguments if you want
//cmd = "site arg1 arg2";
//ftp.sendCommand(cmd);

//Upload file
ftp.uploadSecure(@"Filepath", false);

ftp.close();

Before uploading a file, you have to specify the mode: ftp.setBinaryMode(bool value).

  • value is false --> ASCII mode
  • value is true --> Binary mode

By default, it’s binary. Now, you upload the file using:

C#
ftp.uploadSecure(@"Filepath", false)

Note: you can upload in non secured mode using ftp.upload().

Points of Interest

I learned how an SSL stream and the RAW FTP communication works between a client and an FTP server. Searching on the web, I found many who were stuck on the issue of SSL communication with an FTP server, so I hope this article will be of great help.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

 
GeneralHangs Pin
Member 349382715-Dec-08 10:20
Member 349382715-Dec-08 10:20 
GeneralRe: Hangs [modified] Pin
kadaoui el mehdi15-Dec-08 21:07
kadaoui el mehdi15-Dec-08 21:07 
GeneralRe: Hangs Pin
kawie_45420-Apr-09 6:13
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GeneralRe: Hangs Pin
brian64p27-Apr-09 3:18
brian64p27-Apr-09 3:18 
GeneralRe: Hangs [modified] Pin
sonnguyen7917-Jul-09 12:39
sonnguyen7917-Jul-09 12:39 
GeneralRe: Hangs Pin
freephone5-Jan-10 15:27
freephone5-Jan-10 15:27 

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