我的目标是连接到防火墙后面的服务器（主机）。我可以通过连接到网络中的另一个服务器（隧道）然后SSH到此服务器来访问此服务器。但是我无法通过JSch实现相同的场景。
我无法使用以下代码工作，我为此目的编写了这些代码。如果我在这里做任何蠢事，请告诉我。
public class JschExecutor {
public static void main(String[] args){
JschExecutor t=new JschExecutor();
try{
t.go();
} catch(Exception ex){
ex.printStackTrace();
}
}
public void go() throws Exception{
StringBuilder outputBuffer = new StringBuilder();
String host="xxx.xxx.xxx.xxx"; // The host to be connected finally
String user="user";
String password="passwrd";
int port=22;
String tunnelRemoteHost="xx.xx.xx.xx"; // The host from where the tunnel is created
JSch jsch=new JSch();
Session session=jsch.getSession(user, host, port);
session.setPassword(password);
localUserInfo lui=new localUserInfo();
session.setUserInfo(lui);
session.setConfig("StrictHostKeyChecking", "no");
ProxySOCKS5 proxyTunnel = new ProxySOCKS5(tunnelRemoteHost, 22);
proxyTunnel.setUserPasswd(user, password);
session.setProxy(proxyTunnel);
session.connect(30000);
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand("hostname");
channel.setInputStream(null);
((ChannelExec)channel).setErrStream(System.err);
InputStream in=channel.getInputStream();
BufferedReader ebr = new BufferedReader(new InputStreamReader(in));
channel.connect();
while (true) {
byte[] tmpArray=new byte[1024];
while(in.available()>0){
int i=in.read(tmpArray, 0, 1024);
if(i<0)break;
outputBuffer.append(new String(tmpArray, 0, i)).append("\n");
}
if(channel.isClosed()){
System.out.println("exit-status: "+channel.getExitStatus());
break;
}
}
ebr.close();
channel.disconnect();
session.disconnect();
System.out.println(outputBuffer.toString());
}
class localUserInfo implements UserInfo{
String passwd;
public String getPassword(){ return passwd; }
public boolean promptYesNo(String str){return true;}
public String getPassphrase(){ return null; }
public boolean promptPassphrase(String message){return true; }
public boolean promptPassword(String message){return true;}
public void showMessage(String message){}
}
}
上述代码在session.connect(30000);行上提供了以下例外。
com.jcraft.jsch.JSchException: ProxySOCKS5: com.jcraft.jsch.JSchException: fail in SOCKS5 proxy
at com.jcraft.jsch.ProxySOCKS5.connect(ProxySOCKS5.java:317)
at com.jcraft.jsch.Session.connect(Session.java:231)
at com.ukris.main.JschExecutor.go(JschExecutor.java:50)
at com.ukris.main.JschExecutor.main(JschExecutor.java:19)
Caused by: com.jcraft.jsch.JSchException: fail in SOCKS5 proxy
at com.jcraft.jsch.ProxySOCKS5.connect(ProxySOCKS5.java:200)
... 3 more
答案 0 :(得分：7)
jsch上的SOCKS代理设置允许您连接到远程端的运行代理服务器。远程端的sshd 不会被视为SOCKS代理。您需要做的是在您要隧道连接的机器上建立一个转发到ssh端口的本地端口，然后使用api建立到该系统的辅助ssh连接。
我已经采取了你的例子并稍微重写了它以实现这一目标：
import com.jcraft.jsch.*;
import java.io.*;
public class JschExecutor2 {
public static void main(String[] args){
JschExecutor2 t=new JschExecutor2();
try{
t.go();
} catch(Exception ex){
ex.printStackTrace();
}
}
public void go() throws Exception{
StringBuilder outputBuffer = new StringBuilder();
String host="firstsystem"; // First level target
String user="username";
String password="firstlevelpassword";
String tunnelRemoteHost="secondlevelhost"; // The host of the second target
String secondPassword="targetsystempassword";
int port=22;
JSch jsch=new JSch();
Session session=jsch.getSession(user, host, port);
session.setPassword(password);
localUserInfo lui=new localUserInfo();
session.setUserInfo(lui);
session.setConfig("StrictHostKeyChecking", "no");
// create port from 2233 on local system to port 22 on tunnelRemoteHost
session.setPortForwardingL(2233, tunnelRemoteHost, 22);
session.connect();
session.openChannel("direct-tcpip");
// create a session connected to port 2233 on the local host.
Session secondSession = jsch.getSession(user, "localhost", 2233);
secondSession.setPassword(secondPassword);
secondSession.setUserInfo(lui);
secondSession.setConfig("StrictHostKeyChecking", "no");
secondSession.connect(); // now we're connected to the secondary system
Channel channel=secondSession.openChannel("exec");
((ChannelExec)channel).setCommand("hostname");
channel.setInputStream(null);
InputStream stdout=channel.getInputStream();
channel.connect();
while (true) {
byte[] tmpArray=new byte[1024];
while(stdout.available() > 0){
int i=stdout.read(tmpArray, 0, 1024);
if(i<0)break;
outputBuffer.append(new String(tmpArray, 0, i));
}
if(channel.isClosed()){
System.out.println("exit-status: "+channel.getExitStatus());
break;
}
}
stdout.close();
channel.disconnect();
secondSession.disconnect();
session.disconnect();
System.out.print(outputBuffer.toString());
}
class localUserInfo implements UserInfo{
String passwd;
public String getPassword(){ return passwd; }
public boolean promptYesNo(String str){return true;}
public String getPassphrase(){ return null; }
public boolean promptPassphrase(String message){return true; }
public boolean promptPassword(String message){return true;}
public void showMessage(String message){}
}
}
此代码的作用是创建一个本地端口转发到目标系统上的ssh端口，然后通过它连接。运行hostname命令说明它确实在转发系统上运行。
答案 1 :(得分：0)
这已经过测试，可以正常工作。这就像安全管道一样，最适合用于隧道
String strSshUser = "ssh_user_name"; // SSH loging username
String strSshPassword = "abcd1234"; // SSH login password
String strSshHost = "your.ssh.hostname.com"; // hostname or ip or
// SSH server
int nSshPort = 22; // remote SSH host port number
String strRemoteHost = "your.database.hostname.com"; // hostname or
// ip of
// your
// database
// server
int nLocalPort = 3366; // local port number use to bind SSH tunnel
int nRemotePort = 3306; // remote port number of your database
String strDbUser = "db_user_name"; // database loging username
String strDbPassword = "4321dcba"; // database login password
final JSch jsch = new JSch();
Session session = jsch.getSession(strSshUser, strSshHost, 22);
session.setPassword(strSshPassword);
final Properties config = new Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.connect();
session.setPortForwardingL(nLocalPort, strRemoteHost, nRemotePort);