ftp4j: client.login返回无法识别的SSL消息，是否为明文连接？

Question

这是我的代码

try{
    TrustManager[] trustManager = new TrustManager[] { new X509TrustManager() {
        public X509Certificate[] getAcceptedIssuers() { return null; }
        public void checkClientTrusted(X509Certificate[] certs, String authType) {}
        public void checkServerTrusted(X509Certificate[] certs, String authType) {}
    } };

    SSLContext sslContext = null;

    sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, trustManager, new SecureRandom());
    SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
    FTPClient client = new FTPClient();

    client.setSSLSocketFactory(sslSocketFactory);
    client.setSecurity(FTPClient.SECURITY_FTPES);

    client.connect("xxx.xxx.xxx", 21);
    System.out.println("Connected (" + client.isConnected() + ") to host " + client.getHost() + ":" + client.getPort());
    client.login("xxxxx", "xxxxx");            
}catch (Exception e) {
    e.printStackTrace();
}

它在运行时返回

Connected (true) to host xxx.xxx.xxx:21

然后在client.login("xxxxx"，“xxxxx”)上中断；

javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?

知道为什么会这样吗？

java版本为1.4.2，ftp4j版本为1.7.2

Answer 1

信息是明确的。您正在与明文对等方对话SSL。该主机的端口21上是否真的有FTPS服务器？

Answer 2

请确保使用正确的安全设置，例如FTPClient.SECURITY_FTPS或FTPClient.SECURITY_FTPES

FTPS (基于隐式

/SSL)和FTPES (基于显式TLS/SSL)