Setting up your computer so that it is "connected to the internet" is simple if you have only one computer and it is connected directly to the internet, typically via a dial-up connection or a DSL/cable service that plugs directily into your computer. You run ACP, your email, your web browser, and whatever other goodies you routinely use (internet telephones, instant messagers, etc.), all on one computer.
It's more likely that you'll have a more-or-less dedicated computer for running the observatory and one or more other computers for data reduction, general use by family members, etc. Once you break free from trying to use one computer for everything you do, you enter the territory of home networking.
It's beyond the scope of the Share Your Sky! web site to provide tutorials, assistance, and reference material on home networking. In the right column of this page you'll find a few web resources for home networking. We'll try to start you out on a good footing. Assuming you want to set up a home network, here are some things to consider.
Most Cable and DSL setups that provide service to multiple computers in the home use a separate router. You hook your cable or DSL modem to the router, and then tie the router and your computers together via ethernet. Most of the routers out there double as an ethernet hub with 4 or 8 outlets for your computers.
Home net routers use Network Address Translation (NAT), which isolates your computers from the internet on an "inside" network. The IP addresses on the inside network are typically 192.168.x.x or 10.x.x.x. These IP addresses are non-routable and cannot be used to reach your inside computers from outside. Thus, it is not normally possible for someone outside to establish a TCP network connection to any of your inside computers, including the one running ACP.
What can you do? Virtually all routers allow you to configure them such that one of your inside computers appears on the public/outside internet. This feature is often called "DMZ". The router will route incoming TCP connections to the DMZ computer on your internel net. From the outside, your internal computer will appear to have the IP address of the router, so that's the IP you give to outsiders, not the 192.168.x.x address that is physically assigned to the ACP computer. Note that the router's IP address may chnage from time to time. See the next section.
Most residential internet providers assign IP addresses from a pool at the time you make your connection. Each time you connect, you will get a different IP address. This can make it difficult for your observatory users to contact your servers, as they will have to type in a URL containing the current IP address. If this changes, you'll have to provide a way for your observers to know what URL to use. You can circumvent this problem by using DNS2Go. See the next section.
Whether you have a dynamic or static IP address, it's much easier for your observers to use a domain name to reach your observatory from their browser. Share Your Sky! has formed a partnership with Deerfield Communications, the provider of the DNS2Go service. This service, combined with a small applet you run on your ACP computer, provides your observers with a domain name for your observatory.
Regardless of your IP address (even when it changes dynamically) DNS2Go makes it possible for your observers to use just one domain name in their browsers. Share Your Sky! users get a reserved domain, My-Sky.com, for their internet address. For example, if your observatory was called the Hubble Peak Observatory, you could get something like http://HubblePeak.My-Sky.com/ for your ACP internet address.
DNS2Go is a service which costs $19.95 a year for one domain name (that's all you need for ACP). To get started, install the free My-Sky.com package of DNS2Go, and complete the signup process that you'll see after installation.