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Frequently
Asked Questions about NAT
Q: What is NAT?
A: NAT stands for "Network Address Translation".
Simply put, it allows an internal network (such as a LAN
typically found in an office) to communicate with the Internet
without the use of public Internet IP addresses for every
machine.
Q: What is an IP address?
A: IP stands for "Internet Protocol" and is the
universal method for machines to communicate over the
Internet. All machines on the Internet are given an IP
Address which identifies them to the exclusion of all other
machines on the Internet; similar to how a phone number has
only one destination. IP addresses can also be used in
LANs, such as the ones typically found in offices.
Q: What is a 'Private' IP address?
A: Some addresses on the internet are considered
'private', and cannot be routed on the internet. These
IP addresses have been set aside for use in LAN environments
where a connection to the internet is not desired or not
available. The following are the current 'private'
address spaces on the internet:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
Q: How do I tell if I have private
addresses in my LAN?
A: 1) Double-click "my computer" in the upper
left hand corner of your screen.
(the following screens may differ slightly from
your operating system)
2) Double-click "control panel".
3) Doubleclick "network", you may
have to scroll down.
4) Highlight the line that says "Tcp/Ip
-> (your brand network card)
Click on "properties", hit "ok" on the
warning message.
If the IP number is in these ranges 10.0.0.0
- 10.255.255.255, 172.16.0.0 - 172.31.255.255, 192.168.0.0 -
192.168.255.255 then they are 'private' addresses and are
not suitable for use on the Internet.
Q: How does NAT work?
A: Put simply, when NAT is enabled on a router it will
'translate' or rewrite all of your outbound traffic so it
appears to come from a valid internet IP address. When
traffic is received, traffic will be again rewritten to direct
it to the correct internal machine. The router will
maintain a table of these translations to aid it in correctly
translating traffic.
Q: What are the benefits of using NAT?
A: There are several benefits to using NAT. First of
all, once your machines are given private addresses there is
seldom a need to renumber them later on. NAT also
adds a measure of security to your network because there is no
direct route from the Internet to any of the machines in your
office. NAT also helps to conserve Internet IP
addresses, which are starting to run short.
Q: When should I not use NAT?
A: You should not use NAT if you will require a direct
connection from the internet into more than one or more of your
machines. A typical example would be if you wanted to
use PCAnywhere or some other type of remote access service to
gain access to your network from the Internet, or if you want
to run your own Email or Web server. People with
very large numbers of machines (greater than 100) or who
utilize very high bandwidth may want to look into a standalone
high performance NAT system or an alternate means to get their
traffic onto the internet. |
