[mybest2U]

Hi all,

Just curious, but I thought that my WLAN's internal IP address for my computer (192.168....) was not accessible from the internet, only my router's internet IP address could be seen. But if you go to www.whatsmyip.org, and click on their "more info about me" option, it shows my internal WLAN address, as well as my router's internet IP.

So.... is it my Internet Explorer that provides this info to them, or how do they query for this info? I'm just a little concerned for security reasons.

Thanks for any help!

[TerryNet]

If your computer's IP did not go along as part of the packets that go to an internet site (say, one that requests www.whatsmyip.org to return your info, how would the response get back to you?

It's very similar to wanting somebody to return your phone call or respond to your letter--you need to give them your phone number or mailing address.

[mybest2U]

From the little networking info I've read about, does this then suggest some sort of NAT networking, as opposed to PAT? From what I understand, with PAT, my internal IP address is never made available since my router figures out which computer on my LAN to forward incoming packets based on the incoming TCP port number. But I also thought that outgoing packets only contained a single IP address and port number (which would be the external internet IP of the router), so how then does NAT figure out where to forward incoming packets if the incoming packets only contain the router's IP address, but not my computer's internal LAN address? Again, it seems it would have to rely on the TCP port number.

If any one could point me to a good article about NAT/PAT that would clear up my confusion that would be great! Thanks.

[TerryNet]

I think you described things pretty well.

The incoming packets that are in reply to something you initiated will have your LAN address.

Packets originating from outside do not have your LAN address, but have a port number (default 80). You, using port forwarding (or virtual server), have told the router to which LAN address that port should go.

I don't know a good source for all the detail you want. In addition to searching for Network Address Translation and Port Address Translation, you can also get details about packet structure at the different levels by looking into Transaction Control Protocol/Internet Protocol (TCP/IP).

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