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VB.NET 2005 FTP Program - TCPIP and Sockets using wrong ports and not working through Windows Firewall

Posted on 2008-06-16
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Last Modified: 2011-10-03
See the attached code (670 lines)

This class enables FTP ing via visual basic. I got it free on the internet !!  Only problem is, it doesn't work when the target server is running windows firewall.

I caught it in the debugger and the problem is in Private Function CreateDataSocket, on the line "s.Connect(ep)"

The variable "port" in the program is programmatically generated and is a different number each time. Windows firewall is also rejecting other ports as in the below pfirewall.log:

#Version: 1.5
#Software: Microsoft Windows Firewall
#Time Format: Local
#Fields: date time action protocol src-ip dst-ip src-port dst-port size tcpflags tcpsyn tcpack tcpwin icmptype icmpcode info path

2008-06-16 16:48:23 DROP TCP 99.99.108.178 99.99.163.114 3104 1196 48 S 507753288 0 65535 - - - RECEIVE
2008-06-16 16:48:32 DROP TCP 99.99.108.178 99.99.163.114 3104 1196 48 S 507753288 0 65535 - - - RECEIVE
2008-06-16 16:48:26 DROP TCP 99.99.108.178 99.99.163.114 3104 1196 48 S 507753288 0 65535 - - - RECEIVE
2008-06-16 17:59:07 DROP TCP 99.99.108.178 99.99.163.114 3126 1048 48 S 2942101445 0 65535 - - - RECEIVE
2008-06-16 17:59:04 DROP TCP 99.99.108.178 99.99.163.114 3126 1048 48 S 2942101445 0 65535 - - - RECEIVE
2008-06-16 17:59:13 DROP TCP 99.99.108.178 99.99.163.114 3126 1048 48 S 2942101445 0 65535 - - - RECEIVE

So ports 1196 and 1048 were attempted on different calls.

Any ideas how to fix this program so it can work just through port 21 ?

thanks

Public Class Ftp
 
    Private m_sRemoteHost, m_sRemotePath, m_sRemoteUser As String
    Private m_sRemotePassword, m_sMess As String
    Private m_iRemotePort, m_iBytes As Int32
    Private m_objClientSocket As System.Net.Sockets.Socket
 
    Private m_iRetValue As Int32
    Private m_bLoggedIn As Boolean
    Private m_sMes, m_sReply As String
 
    'Set the size of the packet that is used to read and to write data to the FTP server
    'to the following specified size.
    Public Const BLOCK_SIZE As Integer = 512
    Private m_aBuffer(BLOCK_SIZE) As Byte
    Private ASCII As System.Text.Encoding = System.Text.Encoding.ASCII
    Public flag_bool As Boolean
    'General variable declaration
    Private m_sMessageString As String
 
    ' Parameterized constructor
    Public Sub New(ByVal sRemoteHost As String, _
                   ByVal sRemoteUser As String, _
                   ByVal sRemotePassword As String, _
                   ByVal iRemotePort As Int32, _
                   ByVal sRemotePath As String)
        m_sRemoteHost = sRemoteHost
        m_sRemotePath = sRemotePath
        m_sRemoteUser = sRemoteUser
        m_sRemotePassword = sRemotePassword
        m_sMessageString = ""
        m_iRemotePort = iRemotePort
        m_bLoggedIn = False
    End Sub
 
 
    'Set or Get the name of the FTP server that you want to connect.
    Public Property RemoteHostFTPServer() As String
        'Get the name of the FTP server.
        Get
            Return m_sRemoteHost
        End Get
        'Set the name of the FTP server.
        Set(ByVal Value As String)
            m_sRemoteHost = Value
        End Set
    End Property
 
    'Set or Get the FTP Port Number of the FTP server that you want to connect.
    Public Property RemotePort() As Int32
        'Get the FTP Port Number.
        Get
            Return m_iRemotePort
        End Get
        'Set the FTP Port Number.
        Set(ByVal Value As Int32)
            m_iRemotePort = Value
 
        End Set
    End Property
 
    'Set or Get the remote path of the FTP server that you want to connect.
    Public Property RemotePath() As String
        'Get the remote path.
        Get
            Return m_sRemotePath
        End Get
        'Set the remote path.
        Set(ByVal Value As String)
            m_sRemotePath = Value
        End Set
    End Property
 
    'Set or Get the remote password of the FTP server that you want to connect.
    Public Property RemotePassword() As String
        Get
            Return m_sRemotePassword
        End Get
        Set(ByVal Value As String)
            m_sRemotePassword = Value
        End Set
    End Property
 
    'Set or Get the remote user of the FTP server that you want to connect.
    Public Property RemoteUser() As String
        Get
            Return m_sRemoteUser
        End Get
        Set(ByVal Value As String)
            m_sRemoteUser = Value
        End Set
    End Property
 
    'Set the class MessageString.
    Public Property MessageString() As String
        Get
            Return m_sMessageString
        End Get
        Set(ByVal Value As String)
            m_sMessageString = Value
        End Set
    End Property
 
    'Return a list of files in a string() array from the file system.
    Public Function GetFileList(ByVal sMask As String) As String()
        Dim cSocket As System.Net.Sockets.Socket
        Dim bytes As Int32
        Dim seperator As Char = ControlChars.Lf
        Dim mess() As String
 
        m_sMes = ""
        'Check if you are logged on to the FTP server.
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
 
        cSocket = CreateDataSocket()
        'Send an FTP command,
        SendCommand("NLST " & sMask)
 
        If (Not (m_iRetValue = 150 Or m_iRetValue = 125)) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        m_sMes = ""
        Do While (True)
            Array.Clear(m_aBuffer, 0, m_aBuffer.Length)
            bytes = cSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
            m_sMes += ASCII.GetString(m_aBuffer, 0, bytes)
 
            If (bytes < m_aBuffer.Length) Then
                Exit Do
            End If
        Loop
 
        mess = m_sMes.Split(seperator)
        cSocket.Close()
        ReadReply()
 
        If (m_iRetValue <> 226) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        Return mess
    End Function
 
    ' Get the size of the file on the FTP server.
    Public Function GetFileSize(ByVal sFileName As String) As Long
        Dim size As Long
 
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command.
        SendCommand("SIZE " & sFileName)
        size = 0
 
        If (m_iRetValue = 213) Then
            size = Int64.Parse(m_sReply.Substring(4))
        Else
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        Return size
    End Function
 
    'Log on to the FTP server.
    Public Function Login() As Boolean
 
        m_objClientSocket = New System.Net.Sockets.Socket(System.Net.Sockets.AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Stream, System.Net.Sockets.ProtocolType.Tcp)
 
        Dim ep As New System.Net.IPEndPoint(Net.IPAddress.Parse(m_sRemoteHost), m_iRemotePort)
 
        Try
            m_objClientSocket.Connect(ep)
        Catch ex As Exception
            MessageString = m_sReply
            Throw New System.IO.IOException("Cannot connect to remote server")
 
        End Try
 
        ReadReply()
        If (m_iRetValue <> 220) Then
            CloseConnection()
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
        'Send an FTP command to send a user logon ID to the server.
        SendCommand("USER " & m_sRemoteUser)
        If (Not (m_iRetValue = 331 Or m_iRetValue = 230)) Then
            Cleanup()
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        If (m_iRetValue <> 230) Then
            'Send an FTP command to send a user logon password to the server.
            SendCommand("PASS " & m_sRemotePassword)
            If (Not (m_iRetValue = 230 Or m_iRetValue = 202)) Then
                Cleanup()
                MessageString = m_sReply
                Throw New System.IO.IOException(m_sReply.Substring(4))
            End If
        End If
 
        m_bLoggedIn = True
        'Call the ChangeDirectory user-defined function to change the folder to the
        'remote FTP folder that is mapped.
        ChangeDirectory(m_sRemotePath)
 
        'Return the final result.
        Return m_bLoggedIn
    End Function
 
    'If the value of mode is true, set the binary mode for downloads. Otherwise, set ASCII mode.
    Public Sub SetBinaryMode(ByVal bMode As Boolean)
 
        If (bMode) Then
            'Send the FTP command to set the binary mode.
            '(TYPE is an FTP command that is used to specify representation type.)
            SendCommand("TYPE I")
        Else
            'Send the FTP command to set ASCII mode.
            '(TYPE is a FTP command that is used to specify representation type.)
            SendCommand("TYPE A")
        End If
 
        If (m_iRetValue <> 200) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
    End Sub
 
    Public Sub SetSiteFileType(ByVal FileType As String)
        Dim cmdString As New System.Text.StringBuilder
        cmdString.Append("site filetype=").Append(FileType)
 
        SendCommand(cmdString.ToString)
 
        If (m_iRetValue <> 200) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
    End Sub
 
    ' Download a file to the local folder of the assembly, and keep the same file name.
    Public Sub DownloadFile(ByVal sFileName As String)
        DownloadFile(sFileName, "", False)
    End Sub
    ' Download a remote file to the local folder of the assembly, and keep the same file name.
    Public Sub DownloadFile(ByVal sFileName As String, _
                            ByVal bResume As Boolean)
        DownloadFile(sFileName, "", bResume)
    End Sub
    'Download a remote file to a local file name. You must include a path.
    'The local file name will be created or will be overwritten, but the path must exist.
    Public Sub DownloadFile(ByVal sFileName As String, _
                            ByVal sLocalFileName As String)
        DownloadFile(sFileName, sLocalFileName, False)
    End Sub
    ' Download a remote file to a local file name and include a path. Then, set the
    ' resume flag. The local file name will be created or will be overwritten, but the path must exist.
    Public Sub DownloadFile(ByVal sFileName As String, _
                            ByVal sLocalFileName As String, _
                            ByVal bResume As Boolean)
        Dim st As System.IO.Stream
        Dim output As System.IO.FileStream
        Dim cSocket As System.Net.Sockets.Socket
        Dim offset, npos As Long
 
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
 
        'SetBinaryMode(True)
 
        If (sLocalFileName.Equals("")) Then
            sLocalFileName = sFileName
        End If
 
        If (Not (System.IO.File.Exists(sLocalFileName))) Then
            st = System.IO.File.Create(sLocalFileName)
            st.Close()
        End If
 
        output = New System.IO.FileStream(sLocalFileName, System.IO.FileMode.Open)
        cSocket = CreateDataSocket()
        offset = 0
 
        If (bResume) Then
            offset = output.Length
 
            If (offset > 0) Then
                'Send an FTP command to restart.
                SendCommand("REST " & offset)
                If (m_iRetValue <> 350) Then
                    offset = 0
                End If
            End If
 
            If (offset > 0) Then
                npos = output.Seek(offset, System.IO.SeekOrigin.Begin)
            End If
        End If
        'Send an FTP command to retrieve a file.
        SendCommand("RETR " & sFileName)
 
        If (Not (m_iRetValue = 150 Or m_iRetValue = 125)) Then
            output.Close()
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        Do While (True)
            Array.Clear(m_aBuffer, 0, m_aBuffer.Length)
            m_iBytes = cSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
            output.Write(m_aBuffer, 0, m_iBytes)
 
            If (m_iBytes <= 0) Then
                Exit Do
            End If
        Loop
 
        output.Close()
        If (cSocket.Connected) Then
            cSocket.Close()
        End If
 
        ReadReply()
        If (Not (m_iRetValue = 226 Or m_iRetValue = 250)) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
    End Sub
 
    ' Delete a file from the remote FTP server.
    Public Function DeleteFile(ByVal sFileName As String) As Boolean
        Dim bResult As Boolean
 
        bResult = True
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command to delete a file.
        SendCommand("DELE " & sFileName)
        If (m_iRetValue <> 250) Then
            bResult = False
            MessageString = m_sReply
        End If
 
        ' Return the final result.
        Return bResult
    End Function
    ' Rename a file on the remote FTP server.
    Public Function RenameFile(ByVal sOldFileName As String, _
                               ByVal sNewFileName As String) As Boolean
        Dim bResult As Boolean
 
        bResult = True
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command to rename a file.
        SendCommand("RNFR " & sOldFileName)
        If (m_iRetValue <> 350) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        'Send an FTP command to rename a file to a file name.
        'It will overwrite if newFileName exists.
        SendCommand("RNTO " & sNewFileName)
        If (m_iRetValue <> 250) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
        ' Return the final result.
        Return bResult
    End Function
 
    'This is a function that is used to create a folder on the remote FTP server.
    Public Function CreateDirectory(ByVal sDirName As String) As Boolean
        Dim bResult As Boolean
 
        bResult = True
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command to make a folder on the FTP server.
        SendCommand("MKD " & sDirName)
        If (m_iRetValue <> 257) Then
            bResult = False
            MessageString = m_sReply
        End If
 
        ' Return the final result.
        Return bResult
    End Function
    ' This is a function that is used to delete a folder on the remote FTP server.
    Public Function RemoveDirectory(ByVal sDirName As String) As Boolean
        Dim bResult As Boolean
 
        bResult = True
        'Check if you are logged on to the FTP server.
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command to remove a folder on the FTP server.
        SendCommand("RMD " & sDirName)
        If (m_iRetValue <> 250) Then
            bResult = False
            MessageString = m_sReply
        End If
 
        ' Return the final result.
        Return bResult
    End Function
    'This is a function that is used to change the current working folder on the remote FTP server.
    Public Function ChangeDirectory(ByVal sDirName As String) As Boolean
        Dim bResult As Boolean
 
        bResult = True
        'Check if you are in the root directory.
        If (sDirName.Equals(".")) Then
            Exit Function
        End If
        'Check if you are logged on to the FTP server.
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
        'Send an FTP command to change the folder on the FTP server.
        SendCommand("CWD " & sDirName)
        If (m_iRetValue <> 250) Then
            bResult = False
            MessageString = m_sReply
        End If
 
        Me.m_sRemotePath = sDirName
 
        ' Return the final result.
        Return bResult
    End Function
    ' Close the FTP connection of the remote server.
    Public Sub CloseConnection()
        If (Not (m_objClientSocket Is Nothing)) Then
            'Send an FTP command to end an FTP server system.
            SendCommand("QUIT")
        End If
 
        Cleanup()
    End Sub
 
    ' Read the reply from the FTP server.
    Private Sub ReadReply()
        m_sMes = ""
        m_sReply = ReadLine()
        m_iRetValue = Int32.Parse(m_sReply.Substring(0, 3))
    End Sub
 
    ' Clean up some variables.
    Private Sub Cleanup()
        If Not (m_objClientSocket Is Nothing) Then
            m_objClientSocket.Close()
            m_objClientSocket = Nothing
        End If
 
        m_bLoggedIn = False
    End Sub
    ' Read a line from the FTP server.
    Private Function ReadLine(Optional ByVal bClearMes As Boolean = False) As String
        Dim seperator As Char = ControlChars.Lf
        Dim mess() As String
 
        If (bClearMes) Then
            m_sMes = ""
        End If
        Do While (True)
            Array.Clear(m_aBuffer, 0, BLOCK_SIZE)
            m_iBytes = m_objClientSocket.Receive(m_aBuffer, m_aBuffer.Length, 0)
            m_sMes += ASCII.GetString(m_aBuffer, 0, m_iBytes)
            If (m_iBytes < m_aBuffer.Length) Then
                Exit Do
            End If
        Loop
 
        mess = m_sMes.Split(seperator)
        If (m_sMes.Length > 2) Then
            m_sMes = mess(mess.Length - 2)
        Else
            m_sMes = mess(0)
        End If
        'TODO fix problem reading zero length field
        If (Not (m_sMes.Substring(3, 1).Equals(" "))) Then
            Return ReadLine(True)
        End If
 
        Return m_sMes
    End Function
    ' This is a function that is used to send a command to the FTP server that you are connected to.
    Private Sub SendCommand(ByVal sCommand As String)
        sCommand = sCommand & ControlChars.CrLf
        Dim cmdbytes As Byte() = ASCII.GetBytes(sCommand)
        m_objClientSocket.Send(cmdbytes, cmdbytes.Length, 0)
        ReadReply()
    End Sub
    ' Create a data socket.
    Private Function CreateDataSocket() As System.Net.Sockets.Socket
        Dim index1, index2, len As Int32
        Dim partCount, i, port As Int32
        Dim ipData, buf, ipAddress As String
        Dim parts(6) As Int32
        Dim ch As Char
        Dim s As System.Net.Sockets.Socket
        Dim ep As System.Net.IPEndPoint
        'Send an FTP command to use a passive data connection.
        SendCommand("PASV")
        If (m_iRetValue <> 227) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        index1 = m_sReply.IndexOf("(")
        index2 = m_sReply.IndexOf(")")
        ipData = m_sReply.Substring(index1 + 1, index2 - index1 - 1)
 
        len = ipData.Length
        partCount = 0
        buf = ""
 
        For i = 0 To len - 1
            If partCount > 6 Then
                Exit For
            End If
            ch = Char.Parse(ipData.Substring(i, 1))
            If (Char.IsDigit(ch)) Then
                buf += ch
            ElseIf (ch <> ",") Then
                MessageString = m_sReply
                Throw New System.IO.IOException("Malformed PASV reply: " & m_sReply)
            End If
 
            If ((ch = ",") Or (i + 1 = len)) Then
                Try
                    parts(partCount) = Int32.Parse(buf)
                    partCount += 1
                    buf = ""
                Catch ex As Exception
                    MessageString = m_sReply
                    Throw New System.IO.IOException("Malformed PASV reply: " & m_sReply)
                End Try
            End If
        Next
 
        ipAddress = parts(0) & "." & parts(1) & "." & parts(2) & "." & parts(3)
 
        ' Make this call in Visual Basic .NET 2002.  You want to
        ' bitshift the number by 8 bits. Therefore, in Visual Basic .NET 2002, you must
        ' multiply the number by 2 to the power of 8.
        'port = parts(4) * (2 ^ 8)
 
        ' Make this call and then comment out the previous line for Visual Basic .NET 2003.
        port = parts(4) << 8
 
        ' Determine the data port number.
        port = port + parts(5)
 
        s = New System.Net.Sockets.Socket(System.Net.Sockets.AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Stream, System.Net.Sockets.ProtocolType.Tcp)
        'ep = New System.Net.IPEndPoint(Dns.Resolve(ipAddress).AddressList(0), port)
        ep = New System.Net.IPEndPoint(Net.IPAddress.Parse(ipAddress), port)
 
        Try
            s.Connect(ep)                     /// ********* THIS IS THE PROBLEM LINE - EP.port is not 21 - so this hits windows firewall and times out ********** ////////
        Catch ex As Exception
            MessageString = m_sReply
            Throw New System.IO.IOException("Cannot connect to remote server")
            'If you cannot connect to the FTP
            'server that is specified, make the boolean variable false.
            flag_bool = False
        End Try
        'If you can connect to the FTP server that is specified, make the boolean variable true.
        flag_bool = True
        Return s
    End Function
 
 
    Public Sub UploadFile(ByVal sFileName As String, ByVal sUploadName As String, _
                              ByVal bResume As Boolean)
        Dim cSocket As System.Net.Sockets.Socket
        Dim offset As Long
        Dim input As System.IO.FileStream
        Dim bFileNotFound As Boolean
 
        If (Not (m_bLoggedIn)) Then
            Login()
        End If
 
        cSocket = CreateDataSocket()
        offset = 0
 
        If (bResume) Then
            Try
                'SetBinaryMode(True)
                offset = GetFileSize(sFileName)
            Catch ex As Exception
                offset = 0
            End Try
        End If
 
        If (offset > 0) Then
            SendCommand("REST " & offset)
            If (m_iRetValue <> 350) Then
 
                'The remote server may not support resuming.
                offset = 0
            End If
        End If
        'Send an FTP command to store a file.
        SendCommand("STOR " & sUploadName)
        If (Not (m_iRetValue = 125 Or m_iRetValue = 150)) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
 
        'Check to see if the file exists before the upload.
        bFileNotFound = False
        If (System.IO.File.Exists(sFileName)) Then
            ' Open the input stream to read the source file.
            input = New System.IO.FileStream(sFileName, System.IO.FileMode.Open)
            If (offset <> 0) Then
                input.Seek(offset, System.IO.SeekOrigin.Begin)
            End If
 
            'Upload the file.
            m_iBytes = input.Read(m_aBuffer, 0, m_aBuffer.Length)
            Do While (m_iBytes > 0)
                cSocket.Send(m_aBuffer, m_iBytes, 0)
                m_iBytes = input.Read(m_aBuffer, 0, m_aBuffer.Length)
            Loop
            input.Close()
        Else
            bFileNotFound = True
        End If
 
        If (cSocket.Connected) Then
            cSocket.Close()
        End If
 
        'Check the return value if the file was not found.
        If (bFileNotFound) Then
            MessageString = m_sReply
            Throw New System.IO.IOException("The file: " & sFileName & " was not found." & _
            " Cannot upload the file to the FTP site.")
 
        End If
 
        ReadReply()
        If (Not (m_iRetValue = 226 Or m_iRetValue = 250)) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If
    End Sub
 
 
End Class

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Question by:plq
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17 Comments
 
LVL 45

Expert Comment

by:sunnycoder
ID: 21801140
       Try
            s.Connect(ep)                     /// ********* THIS IS THE PROBLEM LINE - EP.port is not 21 - so this hits windows firewall and times out ********** ////////

I am not very familiar with VB but shouldn't this work

        Try
            ep.port = 21
            s.Connect(ep)                     /// ********* THIS IS THE PROBLEM LINE - EP.port is not 21 - so this hits windows firewall and times out ********** ////////
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LVL 8

Author Comment

by:plq
ID: 21801210
Thanks Sunny - I appreciate you coming across to vb to help..

Yes I tried that yesterday. It does get further.. The line that actually uploads the ftp file fails with error 425..

        'Send an FTP command to store a file.
        SendCommand("STOR " & sUploadName)
        If (Not (m_iRetValue = 125 Or m_iRetValue = 150)) Then
            MessageString = m_sReply
            Throw New System.IO.IOException(m_sReply.Substring(4))
        End If

in function "UploadFile" then throws an exception because m_iRetVal returned 425 - cant open connection

0
 
LVL 8

Author Comment

by:plq
ID: 21801271
The problem seems to be that the programmer decided to use a "passive data connection", where the server decides the port for you randomly..
So now I am reseaching what an alternative might be ...

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LVL 45

Expert Comment

by:sunnycoder
ID: 21801275
That means you have a control connection in place but cant open a data connection

http://support.microsoft.com/kb/129395

If an FTP error 425 occurs, this indicates that the server was unable to open the connection back to the client. The most likely cause for this is an FTP client application that is attempting to re-use a socket that is still in the TCP TIME-WAIT state due to an earlier connection that hasn't been timed out yet.

Issue appears to be something else
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LVL 8

Author Comment

by:plq
ID: 21801378
I think the problem is that the data connection is opened on a port which is blocked by windows firewall

This thread below seems helpful in understanding why FTP needs 2 ports to work. But then I'm left wondering why FTP.EXE works fine through windows firewall port 21 but my program doesn't

http://www.tcpipguide.com/free/t_FTPDataConnectionManagementNormalActiveandPassiveD-3.htm

The thread states that port 21 is used as the control connection but having a data connection on the same port is "a bad idea" !!

I think creating a "NORMAL" data connection instead of a PASV connection passive connection sound like it might work ?? Or perhaps I should go back to BAT files !

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LVL 45

Expert Comment

by:sunnycoder
ID: 21801416
Is there a firewall on your client machine that is causing issues? Windows FTP.exe might be on white list of this firewall.
The firewall to the remote server should not block outgoing connections.

If that does not work, to be sure that this is not a case of stale connections, can you reboot once and try.
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Author Comment

by:plq
ID: 21801478
No, I'm in a network of about 20 pcs in the uk, and the ftp server is a webserver on ThePlanet...

My network is firewalled with a cisco firewall. I don't think its stale connections as they're not showing up in the server iis and ftp.exe works every time.

The windows firewall log is showing these "ephemeral ports" as rejected, so thats obviously stopping it working.

This thread gives a better clue... but no code showing what SENDCOMMAND commands are needed to use the ftp standard method instead of passive method
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by:plq
ID: 21801480
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Expert Comment

by:rstaveley
ID: 21801513
If you are expecting to do active FTP, you'll need your client to accept a connection from the server.  Generally that's harder to set up in your firewall than passive FTP, which simply requires that your client needs to be able to connect to an unprivileged port > 1023 on the server as well as the privileged command port 21.

Here's a nice explanation: http://slacksite.com/other/ftp.html
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Expert Comment

by:rstaveley
ID: 21801531
Can't you get your firewall set up to allow connections to > 1023 on the FTP servers? Allowing active FTP connections back to your 20 client PCs will be tricky if you are going through NAT.
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by:plq
ID: 21801561
I don't think windows firewall lets you setup a port range, I'd have to create every port from 1023 to 5000 odd manually ??
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Accepted Solution

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plq earned 0 total points
ID: 21801614
Here's a solution

http://www.newagedigital.com/cgi-bin/newagedigital/articles/ms-firewall-ftp.html

1. Run this on the server

C:\Inetpub\AdminScripts>cscript.exe adsutil.vbs set /MSFTPSVC/PassivePortRange "33256-33257"

2. Add ports 33256 and 33257 to windows firewall

Now the program works.

Not ideal to have to open ports but thankfully those ports can be restricted to certain IPs only so not a security risk unless there are more bugs in windows firewall :)


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Expert Comment

by:rstaveley
ID: 21801707
> Not ideal to have to open ports but thankfully those ports can be restricted to certain IPs only so not a security risk unless there are more bugs in windows firewall :)

Those are outbound ports remember. I'm not up to speed with Windows firewall, but I expect that will only set up firewall holes for established connections (i.e. it will not be allow listening for new connections on that port).

Good job you don't have to mess around with the Cisco firewall for this, eh? Network administrators come from the same school of thought as traffic wardens and dictators.
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Expert Comment

by:rstaveley
ID: 21801734
[By the way, no issues here with the point allocation and flagging http:#21801614 as the correct solution in the PAQ.]
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Author Comment

by:plq
ID: 21802244
FYI no they are inbound ports because we are putting settings on the server windows firewall

    vb.net > my dev pc in my network  |  cisco firewall  |  internet   |   TP firewall   |  win firewall on server > server at TP

Windows firewall holes apply to existing connections and new connections but you can lock down to only open that port to certain ip addresses which works for me..

thanks for your help
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