I created a 3 node (1 master, 2 workers) `Apache Spark` cluster in AWS. I'm able to submit jobs to the cluster from the master, however I cannot get it work remotely.

```
/* SimpleApp.scala */
import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark.SparkConf

object SimpleApp {
  def main(args: Array[String]) {
    val logFile = "/usr/local/spark/README.md" // Should be some file on your system
    val conf = new SparkConf().setAppName("Simple Application").setMaster("spark://ec2-54-245-111-320.compute-1.amazonaws.com:7077")
    val sc = new SparkContext(conf)
    val logData = sc.textFile(logFile, 2).cache()
    val numAs = logData.filter(line => line.contains("a")).count()
    val numBs = logData.filter(line => line.contains("b")).count()
    println(s"Lines with a: $numAs, Lines with b: $numBs")
    sc.stop()
  }
}

```

I can see from the master:

```
Spark Master at spark://ip-171-13-22-125.ec2.internal:7077
URL: spark://ip-171-13-22-125.ec2.internal:7077
REST URL: spark://ip-171-13-22-125.ec2.internal:6066 (cluster mode)

```

so when I execute `SimpleApp.scala` from my local machine, it fails to connect to the the `Spark Master`:

```
2017-02-04 19:59:44,074 INFO  [appclient-register-master-threadpool-0] client.StandaloneAppClient$ClientEndpoint (Logging.scala:54)  [] - Connecting to master spark://ec2-54-245-111-320.compute-1.amazonaws.com:7077...
2017-02-04 19:59:44,166 WARN  [appclient-register-master-threadpool-0] client.StandaloneAppClient$ClientEndpoint (Logging.scala:87)  [] - Failed to connect to spark://ec2-54-245-111-320.compute-1.amazonaws.com:7077
org.apache.spark.SparkException: Exception thrown in awaitResult
    at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:77) ~[spark-core_2.10-2.0.2.jar:2.0.2]
    at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:75) ~[spark-core_2.10-2.0.2.jar:2.0.2]
    at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:33) ~[scala-library-2.10.0.jar:?]
    at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59) ~[spark-core_2.10-2.0.2.jar:2.0.2]

```

However, I know it would have worked if I had set the master to `local`, because then it would run locally. However, I want to have my client connecting to this remote master. How can I accomplish that? The Apache configuration looks file. I can even telnet to that public DNS and port, I also configured `/etc/hosts` with the public DNS and hostname for each of the `EC2` instances.
I want to be able to submit jobs to this remote master, what am I missing?