javasshjsch

JSch SFTP code hangs when tranferring a file

My task is to copy some files from server to local, I have searched a lot about connectivity libraries and found JSch. I have used below code but it is taking too much time to read or move the file. I don't know whether it is working or not.

JSch jsch = new JSch();
Session session = null;
try {
    // set up session
    session = jsch.getSession("userName","hostIP");
    // use private key instead of username/password
    session.setConfig(
            "PreferredAuthentications",
            "publickey,gssapi-with-mic,keyboard-interactive,password");
    jsch.addIdentity("***.ppk");
    java.util.Properties config = new java.util.Properties();
    config.put("StrictHostKeyChecking", "no");
    session.setConfig(config);
    session.connect();

    // copy remote log file to localhost.
    ChannelSftp channelSftp = (ChannelSftp) session.openChannel("sftp");
    channelSftp.connect();
    channelSftp.setInputStream(System.in);
    channelSftp.setOutputStream(System.out);
    System.out.println("shell channel connected....");

    ChannelSftp c = (ChannelSftp) channelSftp;

    System.out.println("done");
    channelSftp.get("report.xml", "C:\\Users\\akrishnan");
    channelSftp.exit();

} catch (Exception e) {
    e.printStackTrace();
} finally {
    session.disconnect();
}

Is there any library that I can use to connect the servers from my Java code using private key file (**.ppk)?

Solution

  • This is most likely, what causes the hang:

    channelSftp.setInputStream(System.in);
channelSftp.setOutputStream(System.out);

    Doing that for an "sftp" channel breaks everything. It makes no sense. Just remove those two lines.

    Check the official JSch SFTP example – There are no such calls.

    For a correct code for file transfers using JSch, see: SFTP file transfer using Java JSch.

    Obligatory warning: Do not use StrictHostKeyChecking=no to blindly accept all host keys. That is a security flaw. You lose a protection against MITM attacks.

    For a correct (and secure) approach, see:
    How to resolve Java UnknownHostKey, while using JSch SFTP library?