求可读取.ssh/config的Scala/Java库及等效功能实现方案

Hey there! Let's break down how to replicate your existing SSH config setup in Scala or Java. First, let's recap what your current config does:

Host ip-172-16-*
ProxyCommand ssh jeff@jumpdev.example.org nc %h %p
User ubuntu
IdentityFile ~/.ssh/id_rsa_aws
StrictHostKeyChecking no
ForwardAgent yes

This setup lets you SSH into private EC2 instances like ip-172-16-2-108.ec2.internal as the ubuntu user, routing traffic through the jumpdev.example.org jump host, with agent forwarding enabled and strict host key checking disabled.

To replicate this, we'll use JSch (Java Secure Channel)—a widely used library for SSH operations in JVM languages. Let's walk through the implementation step by step.

Step 1: Add Dependencies #

For Scala (sbt) #

Add this line to your build.sbt to include JSch:

libraryDependencies += "com.jcraft" % "jsch" % "0.1.55"

For Java (Maven) #

Add this dependency block to your pom.xml:

<dependency>
    <groupId>com.jcraft</groupId>
    <artifactId>jsch</artifactId>
    <version>0.1.55</version>
</dependency>

Step 2: Implement the SSH Connection with Jump Host #

Scala Implementation #

import com.jcraft.jsch.{JSch, Session, ChannelExec}
import java.io.File

object SshJumpHostConnector {
  def main(args: Array[String]): Unit = {
    // Match your .ssh/config values here
    val jumpHostUser = "jeff"
    val jumpHost = "jumpdev.example.org"
    val targetHost = "ip-172-16-2-108.ec2.internal"
    val targetUser = "ubuntu"
    val privateKeyPath = System.getProperty("user.home") + "/.ssh/id_rsa_aws"

    val jsch = new JSch()
    // Load the private key for the target EC2 instance
    jsch.addIdentity(privateKeyPath)

    // 1. Establish a session to the jump host first
    val jumpSession: Session = jsch.getSession(jumpHostUser, jumpHost, 22)
    jumpSession.setConfig("StrictHostKeyChecking", "no")
    jumpSession.setConfig("ForwardAgent", "yes")
    // Use public key auth (relies on your local SSH agent for jump host access)
    jumpSession.setConfig("PreferredAuthentications", "publickey")
    jumpSession.connect()

    // 2. Create a proxy using the jump session to route traffic to the target
    val proxy = new com.jcraft.jsch.ProxySOCKS5(jumpHost, jumpSession.getPort)
    proxy.setUserPasswd(jumpHostUser, null)

    // 3. Connect to the target EC2 instance via the proxy
    val targetSession: Session = jsch.getSession(targetUser, targetHost, 22)
    targetSession.setConfig("StrictHostKeyChecking", "no")
    targetSession.setProxy(proxy)
    targetSession.connect()

    println("Successfully connected to the target EC2 instance!")

    // Example: Run a command on the target instance (replace with your setup tasks)
    val channel = targetSession.openChannel("exec").asInstanceOf[ChannelExec]
    channel.setCommand("sudo apt update && echo 'Initial setup step completed!'")
    channel.connect()

    // Read and print the command output
    val inputStream = channel.getInputStream
    val buffer = new Array[Byte](1024)
    var bytesRead = inputStream.read(buffer)
    while (bytesRead != -1) {
      print(new String(buffer, 0, bytesRead))
      bytesRead = inputStream.read(buffer)
    }

    // Clean up resources
    channel.disconnect()
    targetSession.disconnect()
    jumpSession.disconnect()
  }
}

Java Implementation #

import com.jcraft.jsch.*;
import java.io.IOException;
import java.io.InputStream;

public class SshJumpHostConnector {
    public static void main(String[] args) throws JSchException, IOException {
        // Match your .ssh/config values here
        String jumpHostUser = "jeff";
        String jumpHost = "jumpdev.example.org";
        String targetHost = "ip-172-16-2-108.ec2.internal";
        String targetUser = "ubuntu";
        String privateKeyPath = System.getProperty("user.home") + "/.ssh/id_rsa_aws";

        JSch jsch = new JSch();
        // Load the private key for the target EC2 instance
        jsch.addIdentity(privateKeyPath);

        // 1. Establish session to the jump host
        Session jumpSession = jsch.getSession(jumpHostUser, jumpHost, 22);
        jumpSession.setConfig("StrictHostKeyChecking", "no");
        jumpSession.setConfig("ForwardAgent", "yes");
        jumpSession.setConfig("PreferredAuthentications", "publickey");
        jumpSession.connect();

        // 2. Create proxy using the jump session
        Proxy proxy = new ProxySOCKS5(jumpHost, jumpSession.getPort());
        proxy.setUserPasswd(jumpHostUser, null);

        // 3. Connect to target instance via proxy
        Session targetSession = jsch.getSession(targetUser, targetHost, 22);
        targetSession.setConfig("StrictHostKeyChecking", "no");
        targetSession.setProxy(proxy);
        targetSession.connect();

        System.out.println("Successfully connected to the target EC2 instance!");

        // Example: Run setup commands on the target
        ChannelExec channel = (ChannelExec) targetSession.openChannel("exec");
        channel.setCommand("sudo apt update && echo 'Initial setup completed!'");
        channel.connect();

        // Read command output
        InputStream inputStream = channel.getInputStream();
        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            System.out.print(new String(buffer, 0, bytesRead));
        }

        // Clean up
        channel.disconnect();
        targetSession.disconnect();
        jumpSession.disconnect();
    }
}

Key Details Matching Your SSH Config #

• Proxy Routing: Instead of using nc directly, we use JSch's ProxySOCKS5 to route traffic through the jump host session—this achieves the exact same effect as your ProxyCommand line.
• Identity File: We load id_rsa_aws with jsch.addIdentity() to match your IdentityFile config.
• StrictHostKeyChecking: Setting this to "no" disables host key verification, just like your original setup.
• ForwardAgent: Enabling this forwards your local SSH agent through both the jump host and target instance, matching ForwardAgent yes.
• Authentication: The jump host uses your local SSH agent (assuming you have jeff's key loaded), but you can add a separate private key for the jump host if needed.

You can replace the example command with any setup tasks you need to run when connecting to the instance.

内容的提问来源于stack exchange，提问作者ekydfejj