Java

SSH Tunnel Set Allowed Algorithms

See more SSH Tunnel Examples

Demonstrates how to explicitly set the algorithms allowed in the SSH connection protocol for SSH tunneling.

Note: This example requires Chilkat v9.5.0.99 or greater.

Chilkat2 Java

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

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        SshTunnel ssh_tunnel = new SshTunnel();

        JsonObject json = new JsonObject();

        // Here are the algorithms supported by Chilkat at the time this example was written (14-June-2024)

        // ---------------------------
        // SSH Key-Exchange Algorithms
        // ---------------------------
        // curve25519-sha256
        // curve25519-sha256@libssh.org
        // ecdh-sha2-nistp256
        // ecdh-sha2-nistp384
        // ecdh-sha2-nistp521
        // diffie-hellman-group14-sha256
        // diffie-hellman-group16-sha512
        // diffie-hellman-group18-sha512
        // diffie-hellman-group-exchange-sha256
        // diffie-hellman-group1-sha1
        // diffie-hellman-group14-sha1
        // diffie-hellman-group-exchange-sha1

        // ---------------------------
        // SSH Host Key Algorithms
        // ---------------------------
        // ssh-ed25519
        // ecdsa-sha2-nistp256
        // ecdsa-sha2-nistp384
        // ecdsa-sha2-nistp521
        // rsa-sha2-256
        // rsa-sha2-512
        // ssh-rsa
        // ssh-dss

        // ---------------------------
        // SSH Cipher Algorithms
        // ---------------------------
        // chacha20-poly1305@openssh.com
        // aes128-ctr
        // aes256-ctr
        // aes192-ctr
        // aes128-cbc
        // aes256-cbc
        // aes192-cbc
        // aes128-gcm@openssh.com
        // aes256-gcm@openssh.com
        // twofish256-cbc
        // twofish128-cbc
        // blowfish-cbc

        // ---------------------------
        // SSH MAC Algorithms
        // ---------------------------
        // hmac-sha2-256
        // hmac-sha2-512
        // hmac-sha2-256-etm@openssh.com
        // hmac-sha2-512-etm@openssh.com
        // hmac-sha1-etm@openssh.com
        // hmac-sha1
        // hmac-ripemd160
        // hmac-sha1-96
        // hmac-md5

        // Specify the allowed key-exchange, host-key, cipher (i.e. encryption), and mac (i.e. hash) algorithms allowed, in the order of preference.
        // -------------------------------------------------------------------------------------------------------------------------------------------
        // Note: You typically should NOT explicitly set allowed algorithms.
        // By default, Chilkat orders algorithms according to best practices, and pays attention to vulnerabilities such as the "Terrapin Attack".
        // Hard-coding algorthims can make your application brittle and prone to breaking over a long period of time,
        // if a server (at some point in the future) changes its allowed algorithms, or if you connect to a different server,
        // such that the client (Chilkat) and server cannot find a set of mutually agreed-upon algorithms.
        // -------------------------------------------------------------------------------------------------------------------------------------------
        String allowed_kex = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256";
        String allowed_hostKey = "ssh-ed25519,ecdsa-sha2-nistp256";
        String allowed_cipher = "chacha20-poly1305@openssh.com,aes256-ctr";
        String allowed_mac = "hmac-sha2-256,hmac-sha2-512";

        json.updateString("kex", allowed_kex);
        json.updateString("hostKey", allowed_hostKey);
        json.updateString("cipher", allowed_cipher);
        json.updateString("mac", allowed_mac);
        ssh_tunnel.setAllowedAlgorithms(json);

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

        System.out.println("Connected.");

        // ....
        // ....
    }
}