Helping people with computers... one answer at a time.
NAT routers are a fundamental way to share an internet connection while protecting you at the same time. You may already have one. It's easy to check.
I've seen you talk about NAT routers as firewalls, and so on. How do I know if I have one?
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The answer's not as obvious as a lot of people are thinking. Yes, much of the time a NAT router is an additional box ... a device that you plug your computer into that, in turn, plugs into your internet connection. And that box will typically say "router" on it.
But that's not the only way you can end up behind a router.
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As it turns out, many broadband modems also act as a router - and they won't say it on the outside. Knowing whether they're acting as a NAT router is important - you might be able to avoid buying an extra router you don't actually need, or you might be able to avoid installing firewall software you don't actually need.
Finding out is fairly simple.
My favorite way is to open a Command Prompt - that's usually done this way:
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Click on Start
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Click on All Programs
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Click on Accessories
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Click on Command Prompt
You'll probably get window similar to this one:
In that Window type "ipconfig" followed by the enter key, and you should get something like this:
Now, like me, you may have more than one network adapter. The one you probably want to pay attention to is the one labeled Local Area Connection, for wired connections, or Wireless Network Connection if you're running via a WiFi or other wireless connection.
The line you care about is this one:
IP Address. . . . . . . . . . . . : 192.168.1.2
That's your computer's IP address. If it begins with "192.168", as mine does, then you are almost certainly behind a NAT router. IP addresses that begin with "192.168" are actually invalid on the internet as they are specifically intended for non-internet, local networks. The router performs what's called "Network Address Translation", or NAT, to translate from your local IP address to your internet IP address as assigned by your ISP.
You may also see an IP address beginning with "10.", or some addresses beginning with "172." - these, too, may mean that you are behind a router of some sort, but these are typically NOT used by modems and consumer-grade routers. They're typically used for larger installations such as corporations, hotels or some ISPs.
So if your computer is connected directly to your broadband modem, and you have a "192.168." address, then your modem is acting as a NAT router. If you have some other address, then it's not, and you probably want to investigate installing a NAT router or firewall.
Article C2888 - January 4, 2007
Leo A. Notenboom has been playing with computers since he
was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed.
After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers
to common computer and technical questions. More about Leo.
hello, i have a router siemens SL2-141.
i did configure all the ports and stuff, but its a pain in my butt realy, nat makes the network 3 times slower ! i have a static ip adress configured, i have 2 pc's.
one: (static)
10.0.0.2 ip
10.0.0.138 gateway
255.0.0.0 netmask
second (wireless)
10.0.0.1 ip
10.0.0.138 gateway (of course its same ^_^)
255.0.0.0
now i tried the option to remove nat, which blocks all ports.
i did connect to internet, but i didnt actually was, but the router kept recieving, but i didnt recieve it.... i was constantly on my static ip that time, if you could help and tell me how to disable it and making the router work, even if i have to change the router gateway, i must turn it off ! its a pain in my behind O_O
Posted by: ofir at June 20, 2008 10:31 PMI would suggest to use a service like http://www.amibehindnat.com/ that let you know easily through a browser your local and public IP.
Posted by: Lorenzo at August 7, 2008 12:20 PMYou just need a browser with Java capabilities and this can be used also by non technical people.
hello, i treid what u wrote up i become a ip 192.168. but as i search for my ip in internet i become a defferent one and the problem i got ip in usa and i canīt open most of sites that i used to open before please help me what shall i do to return my ip
Posted by: Ihab Zeineddine at December 20, 2008 4:02 PM@Ihab Zeineddine
Posted by: Eric at December 28, 2009 1:44 AMJust use DHCP. It will make your and my life easier.
Reading the screen the Command Prompt brought up, is Ethernet Adapter another name for router? Or a brand of routers? Or something else altogether?
25-Feb-2010
Posted by: Bombay Granny at February 24, 2010 11:20 AM