将文件从Azure网站上传到FTP时，"425无法打开数据连接"

Question

我想将我的Azure Web应用程序创建的文件传输到Azure网络之外的FTP服务器。我得到的只是FTP上的0字节文件和Web应用程序上的“425无法打开数据连接”错误。

Azure Web应用程序或FTP服务器上是否缺少设置？在我的本地IIS Express上使用相同的Web应用程序可以正常工作。该Web应用程序使用ASP。NETMVC5。

编辑1：

这是我用来发送文件的代码：

FtpWebRequest ftpRequest = (FtpWebRequest)WebRequest.Create(ftp + fileName);
ftpRequest.Method = WebRequestMethods.Ftp.UploadFile;
ftpRequest.Credentials = new NetworkCredential(uid, pwd);
ftpRequest.ContentLength = fileBytes.Length;

Stream requestStream = ftpRequest.GetRequestStream();
requestStream.Write(fileBytes, 0, fileBytes.Length);
requestStream.Close();

FtpWebResponse response = (FtpWebResponse)ftpRequest.GetResponse();
var status = response.StatusCode;
response.Close();

根据MSDN，被动模式为默认模式。

编辑2：

启用服务器日志记录这是输出：

System.Net Information: 0 : [60572] FtpControlStream#51898079 - Created connection from <origin_ip> to <destination_ip>.
System.Net Information: 0 : [60572] Associating FtpWebRequest#23597360 with FtpControlStream#51898079
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [220 Microsoft FTP Service]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [USER <user>]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [331 Password required for <user>.]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [PASS *]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [230 User <user> logged in.]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [OPTS utf8 on]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [501 option not supported]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [PWD]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [257 "/" is current directory.]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [TYPE I]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [200 Type set to I.]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [PASV]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [227 Entering Passive Mode (12,106,237,74,4,255).]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Sending command [STOR <file>]
System.Net Information: 0 : [60572] FtpControlStream#51898079 - Received response [425 Can't open data connection.]
System.Net Information: 0 : [60572] FtpWebRequest#23597360::(Releasing FTP connection#51898079.)
System.Net Error: 0 : [60572] Exception in FtpWebRequest#23597360::GetRequestStream - The remote server returned an error: (425) Can't open data connection..
   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)
   at System.Net.FtpWebRequest.GetRequestStream()

编辑3：

另一次尝试：

System.Net Information: 0 : [58636] FtpWebRequest#9144495::.ctor(<ftp_address_and_file>)
System.Net Information: 0 : [58636] FtpWebRequest#9144495::GetRequestStream(Method=STOR.)
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Created connection from <origin_ip> to <destination_ip>.
System.Net Information: 0 : [58636] Associating FtpWebRequest#9144495 with FtpControlStream#57089836
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [220 Microsoft FTP Service]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [USER <user>]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [331 Password required for <user>.]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [PASS *]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [230 User <user> logged in.]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [OPTS utf8 on]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [501 option not supported]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [PWD]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [257 "/" is current directory.]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [TYPE I]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [200 Type set to I.]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [PASV]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Received response [227 Entering Passive Mode (12,106,237,74,5,4).]
System.Net Information: 0 : [58636] FtpControlStream#57089836 - Sending command [STOR <file>]
System.Net Information: 0 : [58636] FtpWebRequest#9144495::(Releasing FTP connection#57089836.)
System.Net Error: 0 : [58636] Exception in FtpWebRequest#9144495::GetRequestStream - The operation has timed out..
   at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)
   at System.Net.FtpWebRequest.RequestCallback(Object obj)
   at System.Net.CommandStream.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)
   at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)
   at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)
   at System.Net.FtpWebRequest.GetRequestStream()

Answer 1

尝试在客户端切换到FTP被动模式。

Answer 2

“无法打开数据连接”是FileZilla FTP服务器在无法打开数据连接进行传输时发出的消息。

通常情况下，当客户端在NAT或防火墙后使用活动FTP模式并向服务器报告其内部IP地址时，不知道服务器无法返回该IP地址。

最简单（通常也是正确的）解决方案是使用FTP被动模式，而不是主动模式。

请参阅我关于FTP连接模式的文章，了解主动模式和被动模式的含义，以及为什么现在每个人都使用被动模式。