Java

SSH Tunnel Per-Client Logging and Client Identifier

Demonstrates the ClientLogDir and ClientIdentifier properties. When ClientLogDir is set, a separate log file is created for each tunnel client; ClientIdentifier is the SSH client-identification string sent during the handshake.

Note: The log paths are relative to the application's current working directory. Absolute paths may also be used.

Background: When many clients share one tunnel, a single combined log is hard to follow, so ClientLogDir gives each connection its own file — the fastest way to diagnose one misbehaving client. ClientIdentifier sets the version string the server sees; overriding the default is occasionally needed for compatibility with servers that key behavior off the client identification, or simply to label your application in server logs.

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Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.SshTunnel;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the SshTunnel per-client logging properties ClientLogDir and ClientIdentifier.

        SshTunnel tunnel = new SshTunnel();

        // When ClientLogDir is set, a separate log file is created for each tunnel client in this
        // directory, which is useful for troubleshooting individual connections.
        tunnel.setClientLogDir("qa_output/client_logs");

        // The SSH client-identification string sent to the SSH server during the handshake.
        tunnel.setClientIdentifier("SSH-2.0-MyTunnelApp_1.0");

        tunnel.setDestHostname("db.internal.example.com");
        tunnel.setDestPort(5432);

        int sshPort = 22;
        try {
            tunnel.connect("ssh.example.com", sshPort);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Normally you would not hard-code the password in source.  You should instead obtain it
        // from an interactive prompt, environment variable, or a secrets vault.
        String password = "mySshPassword";

        try {
            tunnel.authenticatePw("mySshLogin", password);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        int listenPort = 1080;
        try {
            tunnel.beginAccepting(listenPort);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Tunnel running; each client is logged in " + tunnel.getClientLogDir());

        boolean waitForThreadExit = true;
        try {
            tunnel.closeTunnel(waitForThreadExit);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }
    }
}