To manage timeout and keep-alive settings in JSch (a library for SSH connections in Java), you can configure certain properties and methods for the Session object.

Setting Timeout in JSch

The timeout for a session can be configured by calling the setTimeout method on the Session object. This represents the timeout for socket operations (e.g., connection, read).

session.setTimeout(30000); // Timeout value in milliseconds

This means that if the server does not respond within 30 seconds, the session will throw an exception.

---

Enabling Keep-Alive in JSch

To enable keep-alive messages in JSch, you can use two approaches:

1. Server-Side Keep-Alive (TCP KeepAlive)

This setting uses the underlying TCP socket’s keep-alive functionality. It can be enabled like this:

session.setServerAliveInterval(15000); // 15 seconds in milliseconds

• The value is the interval in milliseconds between keep-alive messages sent to the server.
• If the server does not respond, an exception will occur, signaling a broken connection.

Additionally, you can set the maximum number of keep-alive messages sent before the session is terminated:

session.setServerAliveCountMax(3); // Maximum 3 messages before termination

2. Custom Keep-Alive Logic

Instead of relying on setServerAliveInterval, you can manually implement logic to periodically send a “ping” request to the server (using SSH commands or packet-level communication) to keep the session alive.

---

Example: Session with Timeout and Keep-Alive

Here’s how you can combine the timeout and keep-alive settings:

package org.kodejava.jsch;

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;

public class JSchTimeoutExample {
    public static void main(String[] args) {
        try {
            JSch jsch = new JSch();
            Session session = jsch.getSession("username", "host", 22);

            // Set credentials
            session.setPassword("password");

            // Configure session
            session.setConfig("StrictHostKeyChecking", "no");

            // Set timeout (30 seconds)
            session.setTimeout(30000);

            // Enable keep-alive (every 15 seconds)
            session.setServerAliveInterval(15000);

            // Allow up to 3 keep-alive failures before termination
            session.setServerAliveCountMax(3);

            // Connect to the server
            session.connect();

            // Perform your SSH operations here

            // Disconnect when done
            session.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

---

Notes:

1. setTimeout affects the timeout for socket operations like connecting, reading, or writing.
2. setServerAliveInterval is dependent on server support. If the server doesn’t support keep-alive messages, this won’t work.
3. Ensure you configure session.setConfig to disable strict host key checking only in non-production environments or for testing purposes.
4. For production environments, manage key verification more securely by configuring a UserInfo implementation or adding the server’s key to known hosts.