SOLVE
No need to add Inbound or Outbound in Amazon EC2 Security Group.
To run or check the faye connection like in local development (http://localhost:9292) in Amazon EC2.
run/check faye
rails s -b 0.0.0.0
-b is for binding.
See this link, https://github.com/thoughtbot/til/blob/master/docker/binding-to-0-0-0-0-in-rails.md
So, you can now access it using EC2 IP/Elastic IP like http://54.33.222.111:9292.
Then, you will see "Sure you're not looking for /faye ?"
run private_pub
rackup private_pub.ru -s thin -E production -o 0.0.0.0
-o will open ports for your EC2 IP Address.
You can also use external faye server.
As here https://github.com/Hareramrai/fayeserver.
But it seems a little slow in response, so I still used locally.
If you plan to use external faye server, update your private_pub.yml like:
server: "http://ramfayeserver.herokuapp.com/faye"
secret_token: "batkaro"