我正在尝试用java创建到fortigate防火墙的ssl vpn连接。类似于openvpn的东西。我试过用c语言阅读源代码，但没有多大帮助。在java中建立套接字连接不是问题。但是我如何向防火墙进行身份验证并创建vpn隧道呢？不幸的是，我没有在这里找到任何教程或在fortinet的描述。也许有人能帮我。

public static void main(String[] args) throws IOException {

    String vpnHost = "fortigateVPNHost";
    int vpnPort = 443;
    String vpnUser = "vpnUser";
    String vpnPassword = "vpnPassword";
    SSLSocketFactory sslsocketfactory = (SSLSocketFactory) SSLSocketFactory.getDefault();
    SSLSocket sslsocket = (SSLSocket) sslsocketfactory
            .createSocket(vpnHost, vpnPort);
    InputStream in = sslsocket.getInputStream();
    OutputStream out = sslsocket.getOutputStream();
    while (in.available() > 0) {
        System.out.print(in.read());
    }
    System.out.println("Secured connection performed successfully");
}