Provide inputs to individual prompts separately with JSch

Question

The problem is that the SSH connection requires the provision of another userid and password info after the general log in.

I am using JSch to connect to the remote server. It takes input in the form of a InputStream. And this InputStream can only be passed once. This causes problems as the session is interactive.

I've tried passing the input stream as linefeed separate values ("username\npassword\n"). This however does not work. Any suggestions would be welcome. Even if I have to look for a new Java library altogether.

try {
    JSch jsch=new JSch();
    Session session=jsch.getSession( "username1", "host", 22);
    session.setPassword("password1");
    session.setConfig("StrictHostKeyChecking", "no");
    session.connect(30000);
    Channel channel=session.openChannel("shell");           
    String data = "username2\npassword2\n";
    channel.setInputStream(new ByteArrayInputStream(data.getBytes()));
    channel.setOutputStream(System.out);
    channel.connect(3*1000);
} catch (Exception e) {
    e.printStackTrace();
}   

The password is not entered properly and it does not navigate to the next set of instruction displayed by the ssh connection.

However, if I try the same with the system console (System.in) as the input stream, it works as expected.

Answer 1

If I understand your question correctly, it looks like the password is provided too quickly and the way the server is implemented, it discards the input that comes too early (before a prompt).

You may need to wait before sending the password.

channel.connect();
OutputStream out = channel.getOutputStream();
out.write(("username2\n").getBytes());
out.flush();   
Thread.sleep(1000); 
out.write(("password2\n").getBytes());
out.flush();

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A more advanced solution would be to implement an Expect-like functionality.