apache commons ftp连接纯文本但授权SSL

Question

I am attempting to use Apache Commons Net library to connect to an FTP server where the initial connection is plain text (and the file listings), but the authorization and data transfer are SSL. I've verified using CoreFTP that this is the actual behavior of the server. How can I accomplish this with the Apache Commons library.

If I use a plain FTPClient I can get a connection but then I get this message: 503 USER: Server policy requires that all clients be secured.

If I try a FTPSClient this way

 FTPSClient l_ftp = new FTPSClient("SSL", true); l_ftp.setAuthValue("SSL"); l_ftp.connect(l_host, l_port); 

I get this error: javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?

which makes a bit of sense, as the server is expecting a plain text connection and the client is attempting SSL.

If I try this

 FTPSClient l_ftp = new FTPSClient("SSL", false); l_ftp.setAuthValue("SSL"); l_ftp.connect(l_host, l_port); 

I get this:

 javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake Caused by: java.io.EOFException: SSL peer shut down incorrectly 

which I think probably means about the same, server expecting plain text and client expecting SSL.

Is this even possible with the Apache Commons library?

Here is the CoreFTP Log

 Welcome to Core FTP, release ver 2.2, build 1857 (x64) -- © 2003-2014 WinSock 2.0 Mem -- 2,096,632 KB, Virt -- 8,589,934,464 KB Started on Monday October 26, 2015 at 14:18:PM Resolving nnnnnnn.nnnnn.com... Connect socket #900 to 222.222.222.222, port 21... 220 CONNECT:Enterprise Gateway 2.0.02. S48 FTP Server ready... 15:18:25 10-26-2015 AUTH SSL 234 AUTH: command accepted. Securing command channel ... TLSv1, cipher TLSv1/SSLv3 (RC4-MD5) - 128 bit USER omitted 331 Password required for omitted. PASS ********** 230 User omitted logged in. Session Id: 25846. PBSZ 0 200 PBSZ command accepted. PROT C 534 PROT Request denied for policy reasons. PROT cmd failed... CCC 200 CCC command channel is no longer secured. SYST 502 Command not implemented. Keep alive off... PWD 257 "omitted" is the current working Mailbox ID. PASV 227 PASV Entering passive mode (209,95,224,76,121,95). LIST Connect socket #940 to 209.95.224.76, port 31071... 150 Opening data connection. 226 Transfer complete. 0 Bytes sent. Transferred 0 bytes in 0.008 seconds 

Answer 1

This turned out to be some kind of library or some other conflict in the application server I was running in. When I pulled my test code out to a standalone project, it worked fine. For posterity sake, here is the working code.

 FTPSClient l_ftp = new FTPSClient("SSL", false); l_ftp.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out))); l_ftp.setAuthValue("SSL"); l_ftp.connect(l_host, l_port); if (!l_ftp.login(l_username, l_password)) { // BAD! } l_ftp.execPBSZ(0L); l_ftp.execCCC(); l_ftp.pwd(); // DO STUFF l_ftp.logout(); l_ftp.disconnect();