I am using RFC 6238 to generate OTP with slight modification. - authentication

Question

Now i want to send this otp to gmail and from there i have to read the otp and then enter in login page and make authentication sucess.
I am using java API to send mail, this is the program which am using to send mail (apache version 7-local host am using)
package com.otp;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
public class SendMail {
public static void send(String to, String sub, String msg,
final String user, final String pass) {
// create an instance of Properties Class
Properties props = new Properties();
/*
* Specifies the IP address of your default mail server for e.g if you
* are using gmail server as an email sever you will pass smtp.gmail.com
* as value of mail.smtp host. As shown here in the code. Change
* accordingly, if your email id is not a gmail id
*/
props.put("mail.smtp.host", "smtp.gmail.com");
props.put("mail.smtp.socketFactory.port", "465");
props.put("mail.smtp.socketFactory.class",
"javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.port", "465");
props.put("mail.smtp.starttls.enable","true");
/*
* Pass Properties object(props) and Authenticator object for
* authentication to Session instance
*/
Session session = Session.getInstance(props,
new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(user, pass);
}
});
try {
/*
* Create an instance of MimeMessage, it accept MIME types and
* headers
*/
MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress(user));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(
to));
message.setSubject(sub);
message.setText(msg);
/* Transport class is used to deliver the message to the recipients */
Transport.send(message);
} catch (Exception e) {
e.printStackTrace();
}
}
}
But i am getting following Error.
com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.gmail.com, 465; timeout -1;
nested exception is:
java.net.UnknownHostException: smtp.gmail.com
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2054)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:697)
at javax.mail.Service.connect(Service.java:386)
at javax.mail.Service.connect(Service.java:245)
at javax.mail.Service.connect(Service.java:194)
at javax.mail.Transport.send0(Transport.java:253)
at javax.mail.Transport.send(Transport.java:124)
at com.otp.SendMail.send(SendMail.java:60)
at com.otp.Generate.doGet(Generate.java:57)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2522)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2511)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.UnknownHostException: smtp.gmail.com
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:331)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:238)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2020)
... 31 more
How to Resolve it. And make to send the otp code to My Gmail account?
Is There any other method to send the generated otp digit to Gmail or How to resolve The above problem. Please guide me in this issue.