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Jsch 深入浅出(二)

在上面一个帖子里就简单介绍了如何基于jsch实现ssh.

下面就简单介绍一下如何实现FTP的功能通过JSCH.

[java]

public class JftpHandler extends JschHandler {
private static final Logger log = LoggerFactory
.getLogger(JftpHandler.class);

private ChannelSftp sftp = null;

public JftpHandler(String username, String host, int port, String identity) {
super(username, host, port, identity);
}

public JftpHandler(String username, String host, int port, UserInfo userInfo) {
super(username, host, port, userInfo);
}

@Override
public void init() throws JSchException {
super.init();
sftp = (ChannelSftp) session.openChannel(SFTP_PROTOCAL);//sftp
sftp.connect();
log.info("Jftp connection success.");
}

@Override
public void destory() {
if (sftp != null) {
sftp.quit();
sftp.disconnect();
}
super.destory();

log.info("Jftp destory success.");
}

public void cd(String path) throws SftpException {
sftp.cd(path);
}

public void lcd(String path) throws SftpException {
sftp.lcd(path);
}

public String lpwd() {
return sftp.lpwd();
}

public String pwd() throws SftpException {
return sftp.pwd();
}

public void mkdir(String path) throws SftpException {
sftp.mkdir(path);
}

public void rm(String path) throws SftpException {
sftp.rm(path);
}

public void quit() {
sftp.quit();
}

public void rmdir(String path) throws SftpException {
sftp.rmdir(path);
}

public void exit() {
sftp.exit();
}

public void put(String src, String dst, int mode) throws SftpException {
sftp.put(src, dst, mode);
}

public void put(String src, String dst) throws SftpException {
put(src, dst, 0);
}

public void put(String dst) throws SftpException {
put(dst, ".");
}

public void get(String src, String dst) throws SftpException {
sftp.get(src, dst);
}

public void get(String src) throws SftpException {
get(src, ".");
}

/**
* Changes the permissions of one or several remote files.
*
* @param permissions
* @param path
* @throws SftpException
*/
public void chmod(int permissions, String path) throws SftpException {
sftp.chmod(permissions, path);
}

/**
* @returns the protocol version number supported by this client
*/
public String version() {
return sftp.version();
}

}

[/java]

上面的代码只是对JSCH的简单包装,也是对JSCH的抛砖引玉。希望对大家有点用处。。。

Jsch 深入浅出(一)

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:

  1. password
  2. publickey(DSA,RSA)
  3. keyboard-interactive
  4. 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:

[java]

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;
}
}

[/java]

Client

[java]

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
}
}
}

[/java]

测试类

[java]

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();
}

[/java]

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:

[java]

@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();
}

[/java]

上面只是对JSCH的简单介绍,希望对大家有所用户。。。。