Public Internet vs. Your Private Network
There is a key boundary that exists at your router or firewall that acts as a gateway for Internet and network traffic.
- Beyond that line and outside your gateway (router or firewall) is the public world, public DNS, public static and dynamic IP addresses, and your public DNS names for your network.
- Inside that boundary is your own private network and your own private DNS and static IP which is required by Snow Leopard Serve or Lion Server.
Get a Static IP Address and Domain Name
Make sure to set up a static IP (Internet Protocol) address this is a unique address on your local network. Having this static IP will allow port forwarding services from the router to the computer it is hosted on.
In most cases your Mac will have a dynamic IP address. Dynamic addresses change periodically, usually when you restart your computer, while static IP addresses always stay the same.
Public IP numbers
In most cases you will have a public IP address, given to you by your Internet Service Provider (ISP). This is an IP that is unique to you and the entire worldwide Internet.
For example we will give our fictional business or home the public IP address of: 268.135.16.197
In most cases your Internet router will have this public address pre-assigned to it, but your router has to manage the many devices in your home or business network. This is where a private IP address is important. The private IP address allows multiple devices under one public IP address to connect to the Internet and not interfere with each other. With a private IP, your router acts as a switch between the public Internet and your private network. This idea is similar to an apartment complex; it has one public address on the street and designated numbered apartments inside.
Private IP numbers
There are a range of IP addresses that are reserved for private networks and are never given out for public use. The private IP addresses usually start with 192.168, and your router in most cases will be set to 192.168.0.1 or 192.168.1.1 by default. With a private IP address, your router will designate unique addresses within the network range to all Internet connected devices on your network. Your router, having the public Internet address will also use a process called network address translation (NAT). The NAT process will determine which bits of information going to and from the Internet are supposed to link to the specific devices with their own private IP addresses inside your network.
So your network will have a public IP address (in this example it is 268.135.16.197), and your router will also have a private address 192.168.0.1 (for this example). In this configuration the router will designate unique private addresses to your Macs or Mac devices (ie.192.168.0.8) – where the last digit, 8, is the next available address for a particular device, since the router knows that 7 other devices (including the router) work inside your network and will also have IP addresses.
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