java - 如何使用 Java 从一台机器到另一台机器进行 ssh

Question

使用putty，我可以从一台机器到另一台机器，然后从另一台机器进行ssh。就像一个链过程。我想在我的程序中复制相同的内容。到目前为止，我能够ssh到第一台机器。从那台机器我如何 ssh 到后续机器。我还想执行一些命令，如“pwd”或“ls”。

import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import java.io.*;

public class SSH {

   public static void main(String args[]) {

     String user = "******";
     String password = "******";
     String host = "******";
     int port=22;

     String remoteFile="something.txt";

     try {
        JSch jsch = new JSch();
        Session session = jsch.getSession(user, host, port);
        session.setPassword(password);
        java.util.Properties config = new java.util.Properties(); 
        config.put("StrictHostKeyChecking", "no");
        session.setConfig(config);
        session.connect();
        ChannelSftp sftpChannel = (ChannelSftp) session.openChannel("sftp");
        sftpChannel.connect();
        System.out.println("connected to first server....");
        InputStream out= null;
        out= sftpChannel.get(remoteFile);
        BufferedReader br = new BufferedReader(new InputStreamReader(out));
        String line;
        while ((line = br.readLine()) != null)
           System.out.println(line);
        br.close();

        /********* Here i want to ssh to another machine from the already connected one ******/

    String command = "pwd" ; //executing correctly with o/p
    Channel channel = session.openChannel("exec");
    ((ChannelExec) channel).setCommand(command);
    channel.setInputStream(null);
    InputStream in = channel.getInputStream();
    channel.connect();
    byte[] tmp=new byte[1024];
    while(true){
      while(in.available()>0){
        int i=in.read(tmp, 0, 1024);
        if(i<0)break;
        System.out.print(new String(tmp, 0, i));
      }
      if(channel.isClosed()){
        System.out.println("exit-status: "+channel.getExitStatus());
        break;
      }

    }
    channel.disconnect();

    Channel channel1 = session.openChannel("exec");
    ((ChannelExec) channel1).setCommand("ssh username@hostname" + "&&" + "password");//not    executing
    channel1.setInputStream(null);
    in = channel1.getInputStream();
    channel1.connect();
    channel1.disconnect();



    Channel channel2 = session.openChannel("exec");

    ((ChannelExec) channel2).setCommand("ls"); //to verify if ssh to 2nd machine has happened.not working
     channel2.setInputStream(null);
     in = channel2.getInputStream();
    channel2.connect();
   // byte[] tmp=new byte[1024];
    while(true){
      while(in.available()>0){
        int i=in.read(tmp, 0, 1024);
        if(i<0)break;
        System.out.print(new String(tmp, 0, i));
      }
      if(channel.isClosed()){
        System.out.println("exit-status: "+channel2.getExitStatus());
        break;
      }

    }
    channel2.disconnect();
    session.disconnect();
     } catch(Exception e) { System.err.print(e); }
   }

}

Answer 1

在session.connect()之后；使用代码在您的 Linux 服务器中执行命令

                            session.connect();
            command = "pwd;" + "ssh username@hostname" + "&&" + "password" ; // u can give your own commands

            Channel channel = session.openChannel("exec");
            ((ChannelExec) channel).setCommand(command);
            channel.setInputStream(null);
            InputStream in = channel.getInputStream();
            channel.connect();
            byte[] tmp = new byte[1024];
            while (true) {
                while (in.available() > 0) {
                    int i = in.read(tmp, 0, 1024);
                    if (i > 0) {

                        output = new String(tmp, 0, i); // name a variable of your own

                    } else {

                        break;

                    }

                    System.out.println(output);

                }}
                                         channel.disconnect(); 
                                         session.disconnect();

确保断开 channel 。这样您就可以创建一个新 channel 并执行下一个命令。