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EasyDSL Quick IP Tutorial |
The Internet Protocol (IP) allows computers to send and receive data over the Internet. Each computer (also called a host) has a unique IP address (much like each home on a street having a unique postal address). When you request web pages, or send email the request is split into smaller pieces called packets that have your address on it and the address that the packet is sent to. The Internet protocol directs those packets to their intended destination.
Each computer on the Internet has to have the following settings set in its Networking or TCP/IP settings:
Setting up your Network
If you are setting up a router, or proxy server software, you may be using a combination of the following:
Your IP address defines where you are on the Internet. It can either be a Public Address (one that ARIN has assigned to your ISP or to you), or it can be a Private Address, one that has been set aside for use on home or office networks.
Currently, IP addresses are given in the following form: xxx.xxx.xxx.xxx (IPv4)
Public or Routable IP addresses are assigned by ARIN, the American Registry for Internet Numbers. ARIN carefully manages the allocation of IP addresses and there is a whois feature to look up the owners of IP addresses. Routable IP addresses for EasyStreet Customers are assigned by ARIN to EasyStreet, and EasyStreet temporarily assigns them to our customers.
We recommend non-routable IP for home networks. These IP addresses have been set aside for use in home and office networks, when it isn't necessary (or even desirable) to use a public IP address. They are especially useful to the DSL user who has multiple computers connected to a single proxy server, firewall or router (see our Network Overview for details).
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
For more information, see RFC 1918 Address Allocation for Private Internets.
The Subnet Mask defines the size of your network. Effectively, the mask helps tell your computer which addresses to send data to directly and which data to send to the Gateway (to be forwarded to the next hop on the Internet).
The Subnet Mask for most of our DSL accounts is 255.255.255.0
(For the networking professionals: we route the full Class C at our DSL routers).
The Gateway, or Router Address, is the IP address of the machine that connects your computer to the next hop on the Internet. (If you are using private addresses on your network, the Gateway is the internal IP of the machine that directs traffic between your network and the DSL connection).
Each gateway checks the packets coming into it, if it knows where to send that packets, it will send the packet to that network or computer directly. If it doesn't know where to send the packet, it forwards the packet to the router attached to it (another gateway). The next gateway does the same thing, and that is how data is sent through the Internet.
The Gateway address listed on your DSL account information is the IP address of our DSL router at EasyStreet. Usually it is expressed in the form xxx.xxx.xxx.1 (The first 3 sets of numbers match the same set of numbers in your IP address).
Domain Name Servers, also called DNS servers, are a network of servers that keep track of the association between domain names, e.g. easystreet.com, and which IP addresses are used by the that domain name. That allows you to type www.yahoo.com into your web browser and view the yahoo web site, or send email to nobody@easystreet.com.
The EasyStreet DNS servers are 69.30.0.200 and 209.162.195.5
Most people setting multiple computers in their home or office are best served by a network setup that looks like this:
Individual computers are plugged into a router which assigns them non-routable IP addresses, subnet, gateway and DNS information via DHCP and directs traffic to and from their computers with NAT. This setup keeps your home or office network traffic private, and still allows you to get to the Internet.
In addition to setting the DSL (WAN side) IP address on the router, and non routable IP addresses on your network, you may be using a combination of the following, NAT, DHCP, and Port Translation. These are described in more detail below.
On the DSL modem side, or WAN side, of your router, you have a static IP address, from EasyStreet, but inside your network (on the LAN side) it's a good idea to have your router manage your non-routable IP addresses for you, using DHCP. DHCP stands for Dynamic Host Configuration Protocol, and it's a protocol that allows your router to assign computers on your network an IP address, Subnet Mask, Gateway (or Router Address) and the EasyStreet DNS addresses. If you use DHCP, setting up the computers is easy - most of the time they are already configured correctly and you can just plug them into the network, or you may have to set them to "server assigned IP address" in the TCP/IP settings.
Network Address Translation (NAT) allows you to use 1 Routable IP address assigned by us, on your router or proxy server and connect multiple computers (on Non-routable IP addresses) at your home or office.
Different services on the Internet use different ports to communicate. That allows multiple programs doing different things to communicate from the same IP address. The table below gives some common service and the ports they use.
| Service | Port Number |
|---|---|
| HTTP (Web) | 80 |
| FTP | 21 |
| POP mail | 110 |
| SMTP mail | 25 |
Port numbers are used by a variety of applications on the Internet; assigned ports can be looked up in the IANA Port Database.
Some programs (e.g. chat programs, vpn, game software) use dynamic or custom ports to communicate over the Internet. If you are having trouble with one of these programs it's a good idea to check the program's documentation for the port number it uses and make sure that your firewall software will allow traffic on those ports.
Port translation allows you to direct traffic that comes through your router on a particular port to a specific computer on your network. For example, if you have a mail server on your DSL connection you can set port translation to forward traffic for Port 25 to your mail server (instead of having to purchase a separate IP for the mail server). For specific directions see the documentation for your router or proxy server.
In the example above there are two different types of servers, a mail (SMTP) server and a Web (HTTP) Server. Port translation allows you to forward traffic to multiple servers as long as each server is handling services that use different ports.
For more detailed information about Internet Protocols, take a look at Internet Core Protocols: The Definitive Guide
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