IP addresses

[Psycojose]

Ok, sorry, maybe I should have looked through the threads for an answer for this very basic question. I'll learn eventually...
I was under the impression that an IP address is a unique address for every computer or whatever connected to the internet. Like when a certain videogame I used to play I would use my friends IP address so we could connect somewhat directly to eachother.
Now I was setting up a router in my neighbor's apartment (popular linksys router, 54mbps) and I used my computer with a netgear wireless usb adapter to connect to the router after the initial setup. It's address was 192.168.1.1 and it is a default address. So I figured it was just a local address so it didn't need to be unique. But when it assigns me an IP address it is just a variation like 192.168.1.102 or something and I don't see how that could since there are probably thousands of others out there who were probably assigned the same IP address. I figure it is much more complicated than I think. Do you have a link maybe that would elucidate? Or if someone has the time? Is this the correct forum?

[M/Q]

Sure we can help with this, it is actually really easy. There are actually only one truly unique addr and that is called the MAC addr and each individual networking device in the whole world has a unique address. It is typically the goofy looking one with 6 parts xx:xx:xx:xx:xx:xx. Now that said, it is not part of your question, I just wanted to point out that is the only truly unique address.

Now for IP addr's, there are two different kinds. One is called a public or Internet routable IP addr and the other is the private or non-Internet routable addr.

This is a listing of the private IP addr's and you will notice that the ones you mentioned fall under this category.

Private Addresses
..Class A:
....10.0.0.0-10.255.255.255
..Class B:
....172.16.0.0-172.31.255.255
..Class C:
....192.168.0.0-192.168.255.255

These addr's are setup as to never be allowed to gain access to the Internet. The reason being is as you pointed out that there would be a great deal of duplication. The reason all this started was because in the beginning they did not realize how large the Internet would grow, and it came to a point where they were running out of numbers to use for IP addr's. So they came up with the idea of having reusable private IP addrs. So that is why there are two separate sets of addr's

Just to take this a step further, you are probably wondering how the traffic knows where to go. It is the job of the routers, and a technique called NAT or PAT if you get technical. Network Address Translation, is where the router you have has a distinct/unique Internet routable IP addr assigned to its WAN or Internet port. That way anyone on the whole Internet knows how to get to that IP addr. But on the other interface/switch/AP where you have all your internal computers connected, the router hands out those addr's in the private range. To keep this simple, I will just explain the very rudimentary points.

1. You open your browser
2. Select a web site
3. Hit enter
4. Somewhere there is a DNS server that can change the URL name into a specific routable IP addr
5. The DNS server returns that IP addr to your computer
6. Your computer sends this routing info along with the initial web page request to the default gateway or router
7. The router makes note of which IP addr/device placed this request
8. The router replaces the internal IP addr of the computer with its routable IP addr to the request for a web site and sends the request on its way.
9. The routing magic of the Internet and the same process on the other end will then return an answer to the router as its IP addr is the only one known to the world.
10. The router then remembers who asked for that information, removes its IP addr from the data and replaces it with the IP addr of the device/computer that initially asked for it.
11. Then sends it to that computer and the web page displays.

Obviously it is bit more complicated and others may contest my somewhat vague and not totally accurate depiction, but you get the idea.

http://en.wikipedia.org/wiki/Private_IP_address

[Psycojose]

oooh, thank you. Very much I appreciate your help. Things are slowly clearing up for me, steadily.
So I was interested in connecting to my computer and wanted to use this program called Radmin. I started the communication server, but I am not sure how to connect to it. Is it possible? Might only be possible within my private network? Since I am connecting to a wireless router is there a second step? I left my computer connected and the Radmin program running for a night and when I came back to my computer there was a problem, my connection seemed still connected to my access point, but I couldn't access the internet. It did not say limited connectivity or anything. It is possible my friend is having a problem on her side. I have yet to talk to her. I was worried someone might have hacked into my computer using similar software or taking advantage of it, but I might be jumping to conclusions.

[M/Q]

Your computers are in an internal network behind a NAT based router. Only the router has a public IP address. You can access your internal network computers via the Internet. To do this you need to configure 'Forwarding' on the router/firewall. Configure the router to forward connections from a port on the router to a specific IP address and port (Radmin server's default port is 4899) of the target computer in your internal network. You need to assign a port on the router for every computer you need to access. The router will then forward the connection to your computer in the internal network.

[Psycojose]

thanks again for your support, it is really helping me.
Can you tell me how I can find the router's public IP address using my target computer?

[M/Q]

If it was not given to you by the ISP it maybe a dynamic address and change everyonce and awhile. You will have to watch for that. If you want to know the public IP addr of a system log on to that system and using the web browser and go to this website. It will display the public IP address being used by that system

http://www.showmyip.com