java - org.apache.commons.net.ftp.FTPSClient 在列表命令后返回 425

Question

我正在尝试连接到 FTPS 服务器。我可以很好地连接 FileZilla 并列出服务器中的文件、下载等..

我正在尝试使用 org.apache.commons.net.ftp 包中的 FTPSClient 通过 Java 连接到此 FTP 服务器。这就是我正在尝试的方法:

FTPSClient ftp = new FTPSClient();
ftp.connect(HOST, 7021);
ftp.enterLocalPassiveMode();
ftp.login(USERNAME, PASSWORD);
final int list = ftp.list();
System.out.println("List returned: " + list);

我得到的回应是:

List returned: 425

根据Wikipedia , 425 表示:“无法打开数据连接。”

但是，尝试创建文件夹效果很好:

FTPSClient ftp = new FTPSClient();
ftp.connect(HOST, 7021);
ftp.enterLocalPassiveMode();
ftp.login(USERNAME, PASSWORD);
ftp.mkd("/laylaylom");

因此，如果我运行此代码并与 FileZilla 连接，我将在 FTP 服务器中看到文件夹“laylaylom”。

我也尝试过:

FTPSClient ftp = new FTPSClient();
ftp.connect(HOST, 7021);
ftp.login(USERNAME, PASSWORD);
final int pasv = ftp.sendCommand("PASV");
System.out.println("pasv is: " + pasv);
final int list = ftp.list();
System.out.println("List returned: " + list);

输出将是:

pasv is: 227
List returned: 522

其中 227 是:“进入被动模式 (h1,h2,h3,h4,p1,p2)。”维基百科页面中没有列出 552，我不确定它代表什么。

如何使 list() 工作？

编辑#1

在 Martin Prikryl 回答之后我尝试了这个:

FTPSClient ftp = new FTPSClient();
ftp.connect(HOST, 7021);
ftp.enterLocalPassiveMode();
ftp.login(USERNAME, PASSWORD);
final FTPFile[] ftpFiles = ftp.mlistDir("/");
System.out.println(ftpFiles.length);

返回 0..

编辑#2WinSCP 日志:

. 2016-11-24 12:52:33.947 --------------------------------------------------------------------------
. 2016-11-24 12:52:33.947 WinSCP Version 5.9.2 (Build 6958) (OS 6.1.7601 Service Pack 1 - Windows 7 Home Premium)
. 2016-11-24 12:52:33.947 Configuration: HKCU\Software\Martin Prikryl\WinSCP 2\
. 2016-11-24 12:52:33.947 Log level: Normal
. 2016-11-24 12:52:33.947 Local account: KORAYTUGAY6639\koraytugay
. 2016-11-24 12:52:33.947 Working directory: C:\Program Files (x86)\WinSCP
. 2016-11-24 12:52:33.947 Process ID: 3220
. 2016-11-24 12:52:33.947 Command-line: "C:\Program Files (x86)\WinSCP\WinSCP.exe" 
. 2016-11-24 12:52:33.947 Time zone: Current: GMT+2, Standard: GMT+2 (E. Europe Standard Time), DST: GMT+3 (E. Europe Daylight Time), DST Start: 3/27/2016, DST End: 10/30/2016
. 2016-11-24 12:52:33.947 Login time: Thursday, November 24, 2016 12:52:33 PM
. 2016-11-24 12:52:33.947 --------------------------------------------------------------------------
. 2016-11-24 12:52:33.947 Session name: tuimcardtest@files.innbound.net (Ad-Hoc site)
. 2016-11-24 12:52:33.947 Host name: files.innbound.net (Port: 7021)
. 2016-11-24 12:52:33.947 User name: tuimcardtest (Password: Yes, Key file: No)
. 2016-11-24 12:52:33.947 Transfer Protocol: FTP
. 2016-11-24 12:52:33.947 Ping type: Dummy, Ping interval: 30 sec; Timeout: 15 sec
. 2016-11-24 12:52:33.947 Disable Nagle: No
. 2016-11-24 12:52:33.947 Proxy: None
. 2016-11-24 12:52:33.947 Send buffer: 262144
. 2016-11-24 12:52:33.947 UTF: Auto
. 2016-11-24 12:52:33.947 FTPS: Explicit TLS/SSL [Client certificate: No]
. 2016-11-24 12:52:33.947 FTP: Passive: Yes [Force IP: Auto]; MLSD: Auto [List all: Auto]; HOST: Auto
. 2016-11-24 12:52:33.947 Session reuse: Yes
. 2016-11-24 12:52:33.947 TLS/SSL versions: TLSv1.0-TLSv1.2
. 2016-11-24 12:52:33.947 Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
. 2016-11-24 12:52:33.947 Cache directory changes: Yes, Permanent: Yes
. 2016-11-24 12:52:33.947 Recycle bin: Delete to: No, Overwritten to: No, Bin path: 
. 2016-11-24 12:52:33.947 Timezone offset: 0h 0m
. 2016-11-24 12:52:33.947 --------------------------------------------------------------------------
. 2016-11-24 12:52:34.009 Connecting to files.innbound.net:7021 ...
. 2016-11-24 12:52:34.009 Connected with files.innbound.net:7021, negotiating TLS connection...
< 2016-11-24 12:52:34.071 220 Welcome to THE FTP service.
> 2016-11-24 12:52:34.071 AUTH TLS
< 2016-11-24 12:52:34.149 234 Proceed with negotiation.
. 2016-11-24 12:52:34.212 Server asks for authentication with a client certificate.
. 2016-11-24 12:52:34.290 Verifying certificate for "Innflow" with fingerprint 54:52:0f:a0:cc:6a:38:80:d5:52:cc:9d:a4:4f:19:4a:d9:50:08:a7 and 18 failures
. 2016-11-24 12:52:34.290 Asking user:
. 2016-11-24 12:52:34.290 **The server's certificate is not known. You have no guarantee that the server is the computer you think it is.**
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Server's certificate details follow:
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Issuer:
. 2016-11-24 12:52:34.290 - Organization: Innflow, innbound.net, patrick.meier@innflow.com
. 2016-11-24 12:52:34.290 - Location: CH, Zurich, Zurich
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Subject:
. 2016-11-24 12:52:34.290 - Organization: Innflow, innbound.net, patrick.meier@innflow.com
. 2016-11-24 12:52:34.290 - Location: CH, Zurich, Zurich
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Valid: 7/6/2010 11:42:44 PM - 7/3/2020 11:42:44 PM
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Fingerprint (SHA-1): 54:52:0f:a0:cc:6a:38:80:d5:52:cc:9d:a4:4f:19:4a:d9:50:08:a7
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Summary: Self-signed certificate. The error occurred at a depth of 1 in the certificate chain.
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Certificate was not issued for this server. You might be connecting to a server that is pretending to be "files.innbound.net".
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 If you trust this certificate, press Yes. To connect without storing certificate, press No. To abandon the connection press Cancel.
. 2016-11-24 12:52:34.290 
. 2016-11-24 12:52:34.290 Continue connecting and store the certificate? ()
. 2016-11-24 12:52:35.725 Using TLSv1, cipher TLSv1/SSLv3: AES128-SHA, 1024 bit RSA, AES128-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(128)  Mac=SHA1
. 2016-11-24 12:52:35.787 TLS connection established. Waiting for welcome message...
> 2016-11-24 12:52:35.787 USER tuimcardtest
< 2016-11-24 12:52:35.803 331 Please specify the password.
> 2016-11-24 12:52:35.803 PASS ************
< 2016-11-24 12:52:35.865 230 Login successful.
> 2016-11-24 12:52:35.865 SYST
< 2016-11-24 12:52:35.928 215 UNIX Type: L8
> 2016-11-24 12:52:35.928 FEAT
< 2016-11-24 12:52:36.006 211-Features:
< 2016-11-24 12:52:36.006  AUTH SSL
< 2016-11-24 12:52:36.006  AUTH TLS
< 2016-11-24 12:52:36.006  EPRT
< 2016-11-24 12:52:36.006  EPSV
< 2016-11-24 12:52:36.068  MDTM
< 2016-11-24 12:52:36.068  PASV
< 2016-11-24 12:52:36.068  PBSZ
< 2016-11-24 12:52:36.068  PROT
< 2016-11-24 12:52:36.068  REST STREAM
< 2016-11-24 12:52:36.068  SIZE
< 2016-11-24 12:52:36.068  TVFS
< 2016-11-24 12:52:36.068  UTF8
< 2016-11-24 12:52:36.068 211 End
> 2016-11-24 12:52:36.068 OPTS UTF8 ON
< 2016-11-24 12:52:36.131 200 Always in UTF8 mode.
> 2016-11-24 12:52:36.131 PBSZ 0
< 2016-11-24 12:52:36.209 200 PBSZ set to 0.
> 2016-11-24 12:52:36.209 PROT P
< 2016-11-24 12:52:36.271 200 PROT now Private.
. 2016-11-24 12:52:36.287 Connected
. 2016-11-24 12:52:36.287 --------------------------------------------------------------------------
. 2016-11-24 12:52:36.287 Using FTP protocol.
. 2016-11-24 12:52:36.287 Doing startup conversation with host.
> 2016-11-24 12:52:36.349 PWD
< 2016-11-24 12:52:36.411 257 "/"
. 2016-11-24 12:52:36.411 Getting current directory name.
. 2016-11-24 12:52:36.599 Retrieving directory listing...
> 2016-11-24 12:52:36.599 TYPE A
< 2016-11-24 12:52:36.661 200 Switching to ASCII mode.
> 2016-11-24 12:52:36.661 PASV
< 2016-11-24 12:52:36.739 227 Entering Passive Mode (46,140,133,66,195,80).
> 2016-11-24 12:52:36.739 LIST -a
. 2016-11-24 12:52:36.739 Connecting to 46.140.133.66:50000 ...
. 2016-11-24 12:52:36.879 Session ID reused
< 2016-11-24 12:52:36.879 150 Here comes the directory listing.
. 2016-11-24 12:52:36.879 Using TLSv1, cipher TLSv1/SSLv3: AES128-SHA, 1024 bit RSA, AES128-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(128)  Mac=SHA1
. 2016-11-24 12:52:36.911 TLS connection established
. 2016-11-24 12:52:37.020 drwxrwsrwx    6 0        1004         4096 Nov 24 08:32 .
. 2016-11-24 12:52:37.020 drwxrwsrwx    6 0        1004         4096 Nov 24 08:32 ..
. 2016-11-24 12:52:37.020 -rw-r--r--    1 1004     1004       162000 Oct 28 15:25 YTF.AR.T700.S.E0089858.D161028.T092339.A001
. 2016-11-24 12:52:37.020 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:29 abc
. 2016-11-24 12:52:37.020 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:14 koray
. 2016-11-24 12:52:37.020 drwxr-sr-x    2 1004     1004         4096 Nov 24 08:32 laylaylom
. 2016-11-24 12:52:37.020 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:15 tugay
< 2016-11-24 12:52:37.160 226 Directory send OK.
. 2016-11-24 12:52:37.160 Directory listing successful
. 2016-11-24 12:52:37.160 Detecting timezone difference...
. 2016-11-24 12:52:37.160 Retrieving file information...
> 2016-11-24 12:52:37.160 PWD
< 2016-11-24 12:52:37.223 257 "/"
> 2016-11-24 12:52:37.223 CWD /YTF.AR.T700.S.E0089858.D161028.T092339.A001
< 2016-11-24 12:52:37.285 550 Failed to change directory.
> 2016-11-24 12:52:37.285 TYPE I
< 2016-11-24 12:52:37.363 200 Switching to Binary mode.
> 2016-11-24 12:52:37.363 SIZE /YTF.AR.T700.S.E0089858.D161028.T092339.A001
< 2016-11-24 12:52:37.425 213 162000
> 2016-11-24 12:52:37.425 MDTM /YTF.AR.T700.S.E0089858.D161028.T092339.A001
< 2016-11-24 12:52:37.488 213 20161028152533
. 2016-11-24 12:52:37.488 Retrieving file information successful
. 2016-11-24 12:52:37.488 Timezone difference of -3 detected using file /YTF.AR.T700.S.E0089858.D161028.T092339.A001 (Listing: 2016-10-28T12:25:00.000Z, UTF: 2016-10-28T15:25:00.000Z)
. 2016-11-24 12:52:37.488 ..;D;0;1899-12-30T02:00:00.000Z;0;"" [0];"" [0];---------;0
. 2016-11-24 12:52:37.488 YTF.AR.T700.S.E0089858.D161028.T092339.A001;-;162000;2016-10-28T15:25:00.000Z;1;"1004" [0];"1004" [0];rw-r--r--;0
. 2016-11-24 12:52:37.488 abc;D;0;2016-11-24T08:29:00.000Z;1;"1004" [0];"1004" [0];rwxr-sr-x;0
. 2016-11-24 12:52:37.488 koray;D;0;2016-11-24T08:14:00.000Z;1;"1004" [0];"1004" [0];rwxr-sr-x;0
. 2016-11-24 12:52:37.488 laylaylom;D;0;2016-11-24T09:32:00.000Z;1;"1004" [0];"1004" [0];rwxr-sr-x;0
. 2016-11-24 12:52:37.488 tugay;D;0;2016-11-24T08:15:00.000Z;1;"1004" [0];"1004" [0];rwxr-sr-x;0
. 2016-11-24 12:52:37.597 Startup conversation with host finished.
. 2016-11-24 13:54:14.249 Dummy directory read to keep session alive.
. 2016-11-24 13:54:14.249 Retrieving directory listing...
> 2016-11-24 13:54:14.249 TYPE A
< 2016-11-24 13:54:14.312 200 Switching to ASCII mode.
> 2016-11-24 13:54:14.312 PASV
< 2016-11-24 13:54:14.390 227 Entering Passive Mode (46,140,133,66,195,81).
> 2016-11-24 13:54:14.390 LIST -a
. 2016-11-24 13:54:14.390 Connecting to 46.140.133.66:50001 ...
< 2016-11-24 13:54:14.514 150 Here comes the directory listing.
. 2016-11-24 13:54:14.514 Session ID reused
. 2016-11-24 13:54:14.530 Using TLSv1, cipher TLSv1/SSLv3: AES128-SHA, 1024 bit RSA, AES128-SHA              SSLv3 Kx=RSA      Au=RSA  Enc=AES(128)  Mac=SHA1
. 2016-11-24 13:54:14.530 TLS connection established
. 2016-11-24 13:54:14.655 drwxrwsrwx    6 0        1004         4096 Nov 24 08:32 .
. 2016-11-24 13:54:14.655 drwxrwsrwx    6 0        1004         4096 Nov 24 08:32 ..
. 2016-11-24 13:54:14.655 -rw-r--r--    1 1004     1004       162000 Oct 28 15:25 YTF.AR.T700.S.E0089858.D161028.T092339.A001
. 2016-11-24 13:54:14.655 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:29 abc
. 2016-11-24 13:54:14.655 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:14 koray
. 2016-11-24 13:54:14.655 drwxr-sr-x    2 1004     1004         4096 Nov 24 08:32 laylaylom
. 2016-11-24 13:54:14.655 drwxr-sr-x    2 1004     1004         4096 Nov 24 07:15 tugay
< 2016-11-24 13:54:14.795 226 Directory send OK.
. 2016-11-24 13:54:14.795 Directory listing successful

Answer 1

FTP.list method实在是太低级了。它甚至不打开数据连接。它只发送 LIST 命令。您不能单独使用它。正如其文档所述:

A convenience method to send the FTP LIST command to the server,receive the reply, and return the reply code. Remember, it is upto you to manage the data connection. If you don't need this lowlevel of access, use FTPClient, which will handle all low level details for you.

<小时/>

相反，使用一些高级方法，例如:

• FTPClient.mlistDir (推荐，如果服务器支持)或
• FTPClient.listFiles .

<小时/>

并保持您的第一种方法，即调用 FTPClient.enterLocalPassiveMode()。

仅通过向服务器发送PASV命令无法切换到被动模式。您还必须切换客户端。否则客户端和服务器将无法相互通信。

FTPClient.enterLocalPassiveMode 将客户端和服务器都切换到被动模式。

<小时/>

当您使用 FTPS 时，您还需要启用加密数据传输。请注意，Apache Common Net 库默认情况下不会加密数据传输。

ftp.execPBSZ(0);
ftp.execPROT("P").

实际上，如果控制连接已加密，某些服务器(特别是您的服务器)甚至会要求您加密数据传输。