如何在 Java 中通过 TLS/SSL (FTPS) 服务器连接到 FTP

Question

I'm stuck in connecting to FTP over TLS/SSL (FTPS) server. I am using SimpleFTP library through am able to connect FTP server without SSL but could not connect FTPS.

It is giving me this error at line 2 (ftp.connect),

SimpleFTP received an unknown response when connecting to the FTP server:
220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------

and am using below code

SimpleFTP ftp = new SimpleFTP();

// Connect to an FTP server on port 21.
ftp.connect("xxx.xxx.xxx.xxx", 21, "username", "pwd");
//getting error at (ftp.connect) above line

// Set binary mode.
ftp.bin();

// Change to a new working directory on the FTP server.
ftp.cwd("web");
ftp.disconnect();

Answer 1

The SimpleFTP class/library does not support TLS/SSL at all.

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Use the FTPSClient class from the Apache Commons Net library instead.

See the official example for the FTPClient class and just substitute the FTPClient with the FTPSClient .

FTPSClient ftpClient = new FTPSClient();
ftpClient.connect(host);
ftpClient.login(user, password);

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The FTPSClient class defaults to an explicit TLS/SSL (recommended). In a rare case you need an implicit TLS/SSL, use new FTPSClient(true) .