Recently needed to read and modify Huawei router configurations using Java, connecting via SSH to send commands and read responses.

1. Add mwiede/jsch Dependency

If using Maven, add the following dependency to your pom.xml file:

<dependencies>
    <dependency>
        <groupId>com.github.mwiede</groupId>
        <artifactId>jsch</artifactId>
        <version>0.2.15</version>
    </dependency>
</dependencies>

If using Gradle, add to your build.gradle file:

dependencies {
    implementation 'com.github.mwiede:jsch:0.2.15'
}

2. Create SSH Connection Using JSch, Execute Commands and Return Responses

/**
 * Get SSH command response
 * @param userName    Username
 * @param password    Password
 * @param host        IP address
 * @param port        Port
 * @param commandList Command list
 */
public String getShellCmdRes(String userName, String password, String host, Integer port, List<String> commandList)
        throws JSchException, IOException {
    StringBuilder stringBuilder = new StringBuilder();
    JSch jsch = new JSch();
    Session session = jsch.getSession(userName, host, port);
    session.setPassword(password);
    session.setConfig("StrictHostKeyChecking", "no");
    session.connect();

    ChannelShell channel = (ChannelShell) session.openChannel("shell");

    // Get input and output streams
    OutputStream inputStreamForTheChannel = channel.getOutputStream();
    InputStream outputStreamForTheChannel = channel.getInputStream();

    // Connect channel
    channel.connect();

    PrintStream commander = new PrintStream(inputStreamForTheChannel, true);

    byte[] tmp = new byte[1024];
    while (true) {
        while (outputStreamForTheChannel.available() > 0) {
            int i = outputStreamForTheChannel.read(tmp, 0, 1024);
            if (i < 0) {
                break;
            }
            String output = new String(tmp, 0, i);
            // Read response
            stringBuilder.append(output);
            stringBuilder.append(System.lineSeparator());
            // Send commands
            commandList.forEach(commander::println);
        }
        if (channel.isClosed()) {
            if (outputStreamForTheChannel.available() > 0) {
                continue;
            }
            break;
        }
        try {
            Thread.sleep(10);
        } catch (Exception ignored) {
        }
    }

    // Close channel and session
    channel.disconnect();
    session.disconnect();
    return stringBuilder.toString();
}

3. Calling the Method Above

3.1 Single Command

Remember to add an exit statement at the end. For routers, use quit to exit:

List<String> commandList = new ArrayList<>();
// View
commandList.add("display bfd session all");
// Exit session
commandList.add("quit");
// Get response
String response = getShellCmdRes("admin", "admin", "1.1.1.1", 22, commandList);

3.2 Multiple Commands

For multiple commands, each time you enter a session, you need an additional quit statement:

List<String> commandList = new ArrayList<>();
// Enter system-view
commandList.add("system-view");
// Enter Tunnel 0/0/5
commandList.add("interface Tunnel 0/0/5");
// View information
commandList.add("display this");
// Exit Tunnel 0/0/5
commandList.add("quit");
// Exit system-view
commandList.add("quit");
// Exit session
commandList.add("quit");
// Get response
String response = getShellCmdRes("admin", "admin", "1.1.1.1", 22, commandList);