How to configure direct http access to EC2 instance?

Question

This is a very basic Amazon EC2 question, but I\'m stumped so here goes.

I want to launch an Amazon EC2 instance and allow access to HTTP on ports 80 and 8888 from a

Answer 1

The standard tcp sockets interface requires that you bind to a particular IP address when you send or listen. There are a couple of somewhat special addresses: localhost (which you're probably familiar with) which is 127.0.0.1. There's also a special address, 0.0.0.0 or INADDR_ANY (internet protocol, special shorthand for ANY ADDRESS). It's a way to listen on ANY or more commonly, ALL addresses on the host. This is a way to tell the kernel/stack that you're not interested in a particular IP address.

So, when you're setting up a server that listens to "localhost" you're telling the service that you want to use the special reserved address that can only be reached by users of this host, and while it exists on every host, making a connection to localhost will only ever reach the host you're making the request from.

When you want a service to be reachable everywhere (on a local host, on all interfaces, etc.) you can specify 0.0.0.0.