D'oh!

[James Knott]

Lennart Sorensen wrote:
> On Sun, Jan 20, 2008 at 03:52:08PM -0500, chris-n/jUll39koHNgV/OU4+dkA at public.gmane.org wrote:
>   
>> But don't I have to have a "Device" set to 'Automatically obtain IP address 
>> from DHCP'? Isn't that how I say "yes" to the Internet cable modem (via my 
>> router?) that I do want an IP address on the Internet? 
>>     
>
> No.  Your router gets a DHCP address from the ISP for the cable modem.
> It then masquarades your local network using that IP.  No one behind the
> router needs DHCP since no one behind the router is visible to the
> outside.
>   

????

My router (a linux box) has a real world address. The modem has a
10.x.x.x address. Rogers uses addresses in the 10.x.x.x range for
communications around it's internal network. Fox example, if I do a
traceroute to Yahoo, I get these lines, plus a few more at the Yahoo end.

1 10.11.0.1 7.082 ms 6.737 ms 5.814 ms
2 vl-201.gw03.wlfdle.phub.net.cable.rogers.com (66.185.90.161) 9.586 ms
9.075 ms 11.881 ms
3 te-15-1-0.gw01.wlfdle.phub.net.cable.rogers.com (24.153.5.25) 7.223 ms
10.299 ms 9.148 ms
4 so-2-3-0.gw02.bloor.phub.net.cable.rogers.com (64.71.240.106) 6.814 ms
9.930 ms 8.484 ms
5 so-1-1-0.igw01.chcrmk.phub.net.cable.rogers.com (66.185.80.201) 18.428
ms 21.458 ms 18.615 ms
6 * * *
7 so-1-0-0.pat2.nyc.yahoo.com (216.115.101.159) 42.667 ms 38.064 ms
33.467 ms

Notice that address in line 1? That's the next hop beyond my modem address.

Many people believe the RFC1918 addresses are non-routable, which is
nonsense. They route just fine, but are not supposed to be routed onto
"The Internet". So, Rogers uses them internally and should be filtering
them, to keep them from going to the internet. The same thing happens
with ADSL DSLAM's.


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