如何检查FTP连接？

Question

Is there a simple, fast way to check that a FTP connection (includes host, port, username and password) is valid and working? I'm using C#. Thank you.

Answer 1

try something like this:

FtpWebRequest requestDir = (FtpWebRequest)FtpWebRequest.Create("ftp://ftp.google.com");
requestDir.Credentials = new NetworkCredential("username", "password");
try
{
     WebResponse response = requestDir.GetResponse();
     //set your flag
}
catch
{
}

Answer 2

this is the method I use, let me know if you know a better one.

/*Hola Este es el metodo que utilizo si conoces uno mejor hasmelo saber Ubirajara 100% Mexicano isc.erthal@gmail.com */

private bool isValidConnection(string url, string user, string password)
{
    try
    {
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(url);
        request.Method = WebRequestMethods.Ftp.ListDirectory;
        request.Credentials = new NetworkCredential(user, password);
        request.GetResponse();
    }
    catch(WebException ex)
    {
        return false;
    }
    return true;
}

Answer 3

This might be useful.

  public async Task<bool> ConnectAsync(string host, string user, string password)
    {
        try
        {
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(host);
            request.Credentials = new NetworkCredential(user, password);
            request.UseBinary = true;
            request.UsePassive = true;
            request.KeepAlive = false; // useful when only to check the connection.
            request.Method = WebRequestMethods.Ftp.ListDirectory;
            FtpWebResponse response = (FtpWebResponse) await request.GetResponseAsync();
            return true;
        }
        catch (Exception)
        {
            return false;
        }            
    }

Answer 4

Use either System.Net.FtpWebRequest or System.Net.WebRequestMethods.Ftp to test your connection using your login credentials. If the FTP request fails for whatever reason the appropriate error message will be returned indicating what the problem was (authentication, unable to connect, etc...)

Answer 5

You could try using System.Net.FtpWebRequest and then just check the GetResponseStream method.

So something like

System.Net.FtpWebRequest myFTP = new System.Net.FtpWebRequest

//Add your credentials and ports

try
{
    myFTP.GetResponseStream();
   //set some flags
}
catch ex
{
  //handle it when it is not working
}

Answer 6

This is from the msdn site to diplay files from a server

public static bool DisplayFileFromServer(Uri serverUri)
{
// The serverUri parameter should start with the ftp:// scheme. 
if (serverUri.Scheme != Uri.UriSchemeFtp)
{
    return false;
}
// Get the object used to communicate with the server.
WebClient request = new WebClient();

// This example assumes the FTP site uses anonymous logon.
request.Credentials = new NetworkCredential ("anonymous","janeDoe@contoso.com");
try 
{
    byte [] newFileData = request.DownloadData (serverUri.ToString());
    string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
    Console.WriteLine(fileString);
}
catch (WebException e)
{
    Console.WriteLine(e.ToString());
}
return true;
}