Jsch 深入浅出

 

如果大家熟悉Linux的话，一定对ssh,sftp,scp等命令非常熟悉。ssh是一个安全协议，用来在不同系统或者服务器之间进行安全连接。ssh 在连接和传送的过程中会加密所有的数据。具体的解释，大家可以参考百度百科的文档。地址为：http://baike.baidu.com/view/16184.htm

但是SSH一般是基于客户端的或者Linux命令行的。比如客户端的工具:OpenSSH,putty,SSH Tectia；在linux上大家可以通过ssh username@host连接到所要想连接的主机。但是如果在J2EE中，如何实现SSH呢？进而可以实现SCP,SFTP的功能呢？下面介绍的JSCH就可以实现下边的功能。

JSCH是一个纯粹的用java实现SSH功能的java  library. 官方地址为：http://www.jcraft.com/jsch/

GitHub 地址为:https://github.com/vngx/vngx-jsch

mvn 配置如下：

<dependency> <groupId>com.jcraft</groupId> <artifactId>jsch</artifactId> <version>0.1.46</version> </dependency>

 

下面简单介绍下ＪＳＣＨ的特点：

1.基于ＤＳＡ和ＲＳＡ加密。

2.可以实现４中认证机制。分别是：

(1i): password

(2i): publickey(DSA,RSA)

(3i): keyboard-interactive

(4i): gss-api-with-mic

3.生成public/private key pair.

4.执行bash script 等脚本

5.可以通过HTTP/SOCK5　proxy

6.支持常见SSH1协议和SSH2协议

我们日常用到的JSCH主要是基于是密码认证和private key 认证。

基于密码认证的比较简单。简单代码如下：

 

 

public class JschHandler {
	private static final Logger log = LoggerFactory.getLogger(JschHandler.class);
	
	public static final String SFTP_PROTOCAL = "sftp";
	private String username;
	private String host;
	private int port;
	private String identity;
	private UserInfo userInfo;
	
	private JSch jsch = null;
	protected Session session = null;
	private boolean firstInit = false;
	private int authType = -1;
	
	/**
	 * Private/public key authorization
	 * @param username user account
	 * @param host	server host
	 * @param port	ssh port
	 * @param identity the path of private key file.
	 * @see http://www.jcraft.com/jsch/
	 */
	public JschHandler(String username,String host,int port,String identity){
		this.username = username;
		this.host = host;
		this.port = port;
		this.identity = identity;
		
		firstInit = false;
		jsch = new JSch();
		
		authType = 0 ;
	}
	
	/**
	 * Password authorization
	 * @param username
	 * @param host
	 * @param port
	 * @param userInfo User information for authorization
	 * @see com.jcraft.jsch.UserInfo
	 * @see http://www.jcraft.com/jsch/
	 */
	public JschHandler(String username,String host,int port,UserInfo userInfo){
		this.username = username;
		this.host = host;
		this.port = port;
		this.userInfo = userInfo;
		
		firstInit = false;
		jsch = new JSch();
		authType = 1;
	}
	/**
	 * 
	 * Initialize SSH session.
	 * When the parameters is not right, It will throw an JSchException.
	 * @throws MessageServicerException
	 * @see com.jcraft.jsch.JSch
	 */
	@SuppressWarnings("static-access")
	protected void init() throws JSchException{
		try {
			validate();
			log.info("JSCH identity:"+identity);
			jsch.setLogger(new JschLogger());
			jsch.setConfig("StrictHostKeyChecking", "no");
			
			if(authType==0) jsch.addIdentity(identity);
			session = jsch.getSession(username, host, port);
			
			if(authType==1) session.setUserInfo(userInfo);
			session.connect();
			
			log.info("JSCH session connect success.");
		} catch (JSchException e) {
			log.error(e.getMessage());
			throw e;
		}
	}
	
	/**
	 * Validate parameters
	 * @throws JSchException
	 */
	private void validate() throws JSchException{
		if(firstInit) return;
		if(username==null||username.isEmpty()){
			throw new JSchException("Parameter:username is empty.");
		}
		if(host==null||host.isEmpty()){
			throw new JSchException("Parameter:host is empty.");
		}else{
			try {
				InetAddress inet = InetAddress.getByName(host);
				host = inet.getHostAddress();
				log.info("JSCH connection address:"+host);
			} catch (UnknownHostException e) {
				throw new JSchException(e.getMessage(),e);
			}
		}
		
		if(authType==0&&(identity==null||identity.isEmpty())){
			throw new JSchException("Parameter:identity is empty.");
		}
		
		if(authType==1&&(userInfo==null)){
			throw new JSchException("Parameter:userInfo is empty.");
		}
		
		firstInit = true;
	}
	
	/**
	 * release connections.
	 * @author 
	 */
	protected void destory(){
		if(session!=null) session.disconnect();
		log.info("JSCH session destory");
	}
	private static class JschLogger implements com.jcraft.jsch.Logger{

		@Override
		public boolean isEnabled(int level) {
			return true;
		}

		@Override
		public void log(int level, String message) {
			System.out.println(String.format("[JSCH --> %s]", message));
		}
	}
	
	public void setUserInfo(UserInfo userInfo) {
		this.userInfo = userInfo;
	}
}

    client

 

public static class MyUserInfo implements UserInfo, UIKeyboardInteractive {
		public String getPassword() {
			return null;
		}

		public boolean promptYesNo(String str) {
			Object[] options = { "yes", "no" };
			int foo = JOptionPane.showOptionDialog(null, str, "Warning",
					JOptionPane.DEFAULT_OPTION, JOptionPane.WARNING_MESSAGE,
					null, options, options[0]);
			return foo == 0;
		}

		String passphrase;
		JTextField passphraseField = (JTextField) new JPasswordField(20);

		public String getPassphrase() {
			return passphrase;
		}

		public boolean promptPassphrase(String message) {
			Object[] ob = { passphraseField };
			int result = JOptionPane.showConfirmDialog(null, ob, message,
					JOptionPane.OK_CANCEL_OPTION);
			if (result == JOptionPane.OK_OPTION) {
				passphrase = passphraseField.getText();
				return true;
			} else {
				return false;
			}
		}

		public boolean promptPassword(String message) {
			return true;
		}

		public void showMessage(String message) {
			JOptionPane.showMessageDialog(null, message);
		}

		final GridBagConstraints gbc = new GridBagConstraints(0, 0, 1, 1, 1, 1,
				GridBagConstraints.NORTHWEST, GridBagConstraints.NONE,
				new Insets(0, 0, 0, 0), 0, 0);
		private Container panel;

		public String[] promptKeyboardInteractive(String destination,
				String name, String instruction, String[] prompt, boolean[] echo) {
			panel = new JPanel();
			panel.setLayout(new GridBagLayout());

			gbc.weightx = 1.0;
			gbc.gridwidth = GridBagConstraints.REMAINDER;
			gbc.gridx = 0;
			panel.add(new JLabel(instruction), gbc);
			gbc.gridy++;

			gbc.gridwidth = GridBagConstraints.RELATIVE;

			JTextField[] texts = new JTextField[prompt.length];
			for (int i = 0; i < prompt.length; i++) {
				gbc.fill = GridBagConstraints.NONE;
				gbc.gridx = 0;
				gbc.weightx = 1;
				panel.add(new JLabel(prompt[i]), gbc);

				gbc.gridx = 1;
				gbc.fill = GridBagConstraints.HORIZONTAL;
				gbc.weighty = 1;
				if (echo[i]) {
					texts[i] = new JTextField(20);
				} else {
					texts[i] = new JPasswordField(20);
				}
				panel.add(texts[i], gbc);
				gbc.gridy++;
			}

			if (JOptionPane.showConfirmDialog(null, panel, destination + ": "
					+ name, JOptionPane.OK_CANCEL_OPTION,
					JOptionPane.QUESTION_MESSAGE) == JOptionPane.OK_OPTION) {
				String[] response = new String[prompt.length];
				for (int i = 0; i < prompt.length; i++) {
					response[i] = texts[i].getText();
				}
				return response;
			} else {
				return null; // cancel
			}
		}
	}

 @Test

	public void testSftp() throws JSchException{
		UserInfo userInfo = new MyUserInfo();
		JftpHandler jhandler = new JftpHandler("username","hostname",22,userInfo);
		try {
			jhandler.init();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		String pwd = null;
		try {
			pwd = jhandler.pwd();
		} catch (SftpException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(pwd);
//		jhandler.destory();
	}

 

基于private key 认证的有点费时。关于如何配置private/public key认证，大家通过google来配置。简单流程如下：

1.在linux 下执行ssh-keygen -t dsa /ssh-keygen -t rsa.这样就会成一对对应的public key 和private key.比如id_dsa_1024,id_dsa_1024.pub.

2. 把public key(id_dsa_1024.pub)复制到想要连接的服务器上，放到对应用户的.ssh目录下。

3.

cd ~/.ssh

#将Client的公钥放入Server的信任列表

cat id_dsa_1024.pub >> authorized_keys

#更新权限，很重要

chmod 0600 *从此以后Client SSH登录Server就不要手工输入密码了

配置完成以后，重新登录一下，就可以发现不用输入密码就可以实现远程登录了。

由于现在基于ＳＳＨ协议的算法很多，加密和解密的算法也不一样。目前Jsch只支持OpenSSH和SSH 1生成的private/public key.

所以当你们发现不能通过private/public key认证的时候，不是jsch的问题，而是不能识别的问题。

简单代码如下：

 

 

 

@Test
	public void testSftp() throws JSchException{
		JftpHandler jhandler = new JftpHandler("username","hostname",22,"C:\\data\\id_dsa_2048_a");
		try {
			jhandler.init();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		String pwd = null;
		try {
			pwd = jhandler.pwd();
		} catch (SftpException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println(pwd);
//		jhandler.destory();
	}

 

上面只是对JSCH的简单介绍，希望对大家有所用户。。。。

本文附件下载:
• jsch-0.1.47.zip (291.9 KB)

已有 0 人发表留言，猛击->> 这里<<-参与讨论


ITeye推荐

• —软件人才免语言低担保 赴美带薪读研！—