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- Network NAT Basics |
Desktop remote control from the web is
assisted by a a common networking
technology called NAT (also referred to
as PAT - Port Address Translation).
NAT is an
acronym for Network Address Translation.
It is a commonly used IP translation and
mapping technology. It's a
technology that allows your network to
share internet access. Using a device or
piece of software that implements NAT
allows an entire network to share a
single internet connection over a single
IP address. A single cable mode, DSL
modem, T1, or even 56k modem could
connect all the computers to the
internet simultaneously. Additionally,
NAT keeps your home network fairly
secure from hackers.
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Most NAT devices allow you
to create maps between the internet and your computer
network - this is called
port forwarding. Example: A request on port 80 from
the Internet (looking for a web server on your IP
address) would normally be turned away by a NAT
device. A special mapping can be set up to send that
request from the internet to a specific computer on your
network. One of your LAN computers could host a web
server on the Internet, and another computer (or the
same one) could host an FTP server because the two
services work on different ports. Only a few special
programs on the internet will not work using this
port forwarding system.
For
our
web based PC remote support software, you
would set the port forward to your computer using the port
number you selected or leaving default port number when your account was
created.
NAT is built in to the most
common Internet Connection Sharing technologies around.
Microsoft has built their ICS around it and every Cable/DSL
Broadband Router on the market accomplishes its job with
NAT.
NAT acts as an interpreter
between two networks. In the case of a home network, it sits
between the internet and your home network. The internet is
considered the ‘public’ side and your home network is
considered the ‘private’ side. When a computer in the
private side request data from the public side (the
internet), the NAT device will open a little conduit between
your computer and the destination computer. When the public
computer returns results from the request, it is passed back
through the NAT device to the requesting computer. With our
remote computer
support software the remote computer connects to your
Viewer.
Security: Basic NAT is not a
real firewall?
Basic NAT devices are not real
firewalls, but they are usually considered ‘good enough’ for
most home networks. By not forwarding requests or probes
that originate from the internet to your LAN, a NAT device
blocks most mischief. A simple NAT device can not keep
hackers from running DOS (Denial Of Service) attacks on you,
but individuals rarely get attacked like that. It will keep
out people looking for file shares, rogue mail servers and
web servers, and most port based exploits. Most also protect
against SMURF and WinNuke attacks. With a NAT device and a
good anti-virus program, you should be safe from the most
common kinds of internet attacks.
Stateful packet inspection (SPI)
Some NAT routers have an
advanced form of firewall built in that does 'stateful
packet inspection'. This allows the NAT devices to filter
out specific kinds of data on your router like SYN flood
attacks, IP Spoofing, Teardrop attacks and others. SPI is a
general term that can describe a router that filters more
kinds of attacks than basic NAT by closely examining packet
data structures. Of course, each manufacturer will
implement different kinds of SPI so not all SPI routers are
equal. Routers with SPI can often log attacks.
What If I want to host a
server?
Most NAT devices allow you to
create maps between the Internet and your computer network -
this is called
port forwarding. Example: A request on port 80 from the
Web (looking for a web server on your IP address) would
normally be turned away by a NAT device. A special mapping
can be set up to send that request from the internet to a
specific computer on your network. One of your LAN computers
could host a web server on the Internet, and another
computer (or the same one) could host an FTP server because
the two services work on different ports. Only a few special
programs on the internet will not work using this
port forwarding system.
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