 I don’t have an Internet IP Address! Some ISP's do not assign
real Internet IP address to their customers. This is
getting more and more common - especially with the emerging
broadband technologies. If your broadband IP address starts with
192.168 or 10. and you are connected
directly to the broadband modem - your service provider has you
behind a firewall. This is also known as having a
private IP address instead of a public IP
address.
What The ISP is
Doing
The ISP has probably set
up a NAT router for it’s customers. This router will act as a
firewall between you and the Internet. In the service provider's
eyes, this keeps hackers from reaching your computer directly -
a security measure.
How limiting is
it?
If your ISP has you
behind a NAT router, there is no way for someone on the Internet to
initiate an IP conversation with your computer. That means NO
SERVERS. You can not run a game server, ftp server or web server.
Outgoing VPN connections will most likely not work so forget
connecting to your office LAN over the Internet. Advanced
teleconferencing programs like NetMeeting will not work. ICQ will
not work correctly as well as MSN Messenger file send/receive.
Lastly, some multi-player games will not even allow you to join a
game on the Internet.
This situation is
different than if you ran your own NAT connection sharing box (like
a broadband router) because you have no control over the ISP NAT
router. If it were your own, you could adjust settings in the router
to make most of those applications work properly.
Can anything be
done?
The only thing you can do
is call your ISP to see if you can get a real IP address. If they
can do it, expect a monthly charge. If they tell you no, think about
switching service providers because there is nothing you can do
about it.
Sharing an
Internet connection that has a private IP address
A few unlucky souls have
actually had their ISP provided IP address match the default
settings of their router! For instance, the ISP might assign an IP
address of 192.168.0.5 and your new Linksys router LAN IP address is
192.168.0.1. This will not work because of routing issues. To fix
this, simply change the IP schema of the router to something else -
like 192.168.100.1
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Troubleshooting
Private IP Address
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