Java 使用SSH连接Linux 使用passwd命令修改密码

使用InputStream和OutputStream来获得命令行运行结果和输入内容是首先需要具备的.

然后要解决SSH连接问题.

在OpenSource项目里找到了Ganymed SSH-2 for Java .下载后有例子,但是没有找到有关交互命令的例子.所以自己探索了一下

在网上看有老外讨论用这个如何改密码,基本上的问题都是因为找不到返回的提示

Linux修改密码输入passwd后,首先是输入当前密码,然后是输入两个新密码

如果当前密码输入错误,或者新密码输入不符合系统密码规则要求,会要求重新输入.如果碰到这种情况,程序很容易进入一个不太好控制的循环.

可能一般人都认为输入命令后所有的返回都应该是用session.getStdout();而不是session.getStderr();从方法名称上看确实如此,一个是取得标准输出,一个是取得错误信息.

其实在输入passwd后.

Changing password for user [username].
Changing password for [username]

这两行是需要通过session.getStdout();来获得的.但是后面的

(current) UNIX password:

New UNIX password:

Retype new UNIX password:

这三行是需要使用sessssion.getStderr();来获取的

如果用户输入没有通过系统检测,会返回具体原因,但是都是BAD PASSWORD开始的.

如果最后修改成功了.你也会看到有successfully来表示.这些信息是通过session.getStdout();来获取的.

现在问题很好解决了吧.

写了一个类来完成修改密码的操作

import ch.ethz.ssh2.Connection;
import ch.ethz.ssh2.Session;
import ch.ethz.ssh2.StreamGobbler;
import com.io.Debug;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

public class ChangeEmailPassword {
    private String username = "";
    private String oldpassword = "";
    private Connection conn = null;
    private boolean hasError = false;
    private String ErrorMessage = "";
    private boolean isSuccessfully = false;
    private String SystemMessage = "";
   
    public static final String HOST = "127.0.0.1"; //server ip
    public boolean isSuccessfully(){
        return isSuccessfully;
    }
    public boolean isHasError(){
        return hasError;
    }
    public String getErrorMessage(){
        return ErrorMessage;
    }
    public void setErrorMessage(String msg){
        hasError = true;
        this.ErrorMessage =  msg;
    }
   
    public ChangeEmailPassword(String username,String oldpassword) {
        this.username = username;
        this.oldpassword = oldpassword;
         try{
             conn = new Connection(HOST);
             conn.connect();
           
            boolean isAuthenticated = conn.authenticateWithPassword(username, oldpassword);
            if (isAuthenticated == false) {
                setErrorMessage("Authentication failed.");
                conn=null;
            }
         }catch(Exception e){
             conn.close();
             conn = null;
             System.out.println(e);
         }
    }
    public void setNewPassword(String newpassword) {
        if(hasError){
            return;
        }
        if (conn==null){
            return;
        }
        try{
            Session sess = conn.openSession();
            sess.execCommand("passwd");
            InputStream so = sess.getStdout();
            InputStream err = sess.getStderr();
            OutputStream out = sess.getStdin();
           
            byte[] buffer = new byte[500];//其实没有必要这么大.130就差不多了.怕万一有什么提示.
            int length = 0;
            length = err.read(buffer);
//            if (length > 0) {
//                System.out.println("#1:"+ new String(buffer, 0, length));
//                //(current) UNIX password:
//            }
            String coldpassword = oldpassword+"\n";
            out.write(coldpassword.getBytes());
            length = err.read(buffer);
//            if (length > 0) {
//                System.out.println("#2:"+ new String(buffer, 0, length));
//                //(current) UNIX password:
//            }
            String cnewpass = newpassword +"\n";
            out.write(cnewpass.getBytes());
            length = err.read(buffer);
            if (length > 0) {
                String rs = new String(buffer, 0, length);
                //System.out.println("#3:"+rs);
                if(rs.indexOf("BAD")>-1){
                    sess.close();
                    conn.close();
                    setErrorMessage(rs);
                    return;
                }
            }
            out.write(cnewpass.getBytes());
            length = so.read(buffer);
            if (length > 0) {
                String rs = new String(buffer, 0, length);
                if(rs.indexOf("successfully")>-1){
                    this.isSuccessfully = true;
                    this.SystemMessage = rs;
                }
            }
           
            sess.close();
           
            conn.close();
        } catch (IOException e) {
            e.printStackTrace(System.err);
        }
    }
   
    public static void main(String[] args) {
        ChangeEmailPassword cep = new ChangeEmailPassword("username", "oldpassword");
        if(cep.isHasError()){
            System.out.println(cep.getErrorMessage());
            cep = null;
            return;
        }
        cep.setNewPassword("newpassword");
        if(cep.isHasError()){
            System.out.println(cep.getErrorMessage());
            cep = null;
            return;
        }
        if(cep.isSuccessfully){
            System.out.println(cep.getSystemMessage());
        }
    }
   
    public String getSystemMessage() {
        return SystemMessage;
    }
}
 
//把里面注解掉的System.out.println打开可以看到系统提示的信息.我只保留了最关键的信息提示