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Old August 12th 18, 06:50 AM posted to alt.comp.os.windows-10
chris[_5_]
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On Fri, 10 Aug 2018 08:47:46 -0400, "Mayayana"
wrote:

"chris" wrote

| I was under
| the impression that a cable connection is actually
| part of a party line, with hundreds of other customers
| sharing the same IP address.
|
| Not sure how cable companies do it, but ADSL and fibre connections all
have
| an IP allocated to them from the pool that their service provider owns. I
| imagine cable is not that different.
|

I wonder. There's been talk for some time of IP4
addresses being short.


https://en.wikipedia.org/wiki/IPv4_address_exhaustion


And as Char noted, in the
early days of cable, neighbors used to find each
other in their Network Neighborhood. It seems that
it would be cheaper and allow for more expansion
if cable companies can share IP addresses across
a group.


It's easier to give everyone a unique IP address. Large scale NAT is
called "Carrier Grade NAT" (CGNAT), but most ISPs don't want to deal
with its complexities, nor do they have the hardware or the capabilities
to do so. NAT in a SoHo router is one thing; NAT for an entire ISP is a
whole different world.


So it seems farfetched that everyone
online could have their own IP address. But I don't
know the details of how it works. I thought maybe
someone else might.


It's not farfetched at all, and lots of people know how it works. What
questions do you have?


| Many websites don't even
| have their own IP address.
|
| False. All web domains have an IP address.
| Again by definition.

They have an IP address by definition, but not
necessarily a dedicated IP address, which is what
I'm wondering about.


It's called virtual hosting.
https://en.wikipedia.org/wiki/Virtual_hosting

IIS, Internet Information Services, is included with every version of
Windows. IIS supports virtual hosting, so you can test it there. Just
create multiple sites in IIS, all using the same IP but different root
folders. IIS will check the Host header on each request to see which
site is being requested.


If you look at webhosting options you'll see that
a dedicated IP is sometimes an option. Probably the
cheapo servers like Dreamhost don't even offer it.
That limits how many customers they can have.


Not really. Putting it another way, virtual hosting limits the number of
IP address that are required.


And IP4 addresses have already run out.


No, they haven't.
https://en.wikipedia.org/wiki/IPv4_address_exhaustion


Shared IP means aaa.com, bbb.com and
ccc.com can all have the same IP address, which
points to their server. A requested page would
then be determined from the GET. So Dreamhost
doesn't have to dedicate either a device or an IP
to an individual customer. They just put each domain
in a separate folder on one machine and figure it
out as the GETS come in.


You're talking about the Host header, which is mandatory in HTTP/1.1
requests (what you call GETs). You can see it with any HTTP-aware tool.
The easiest is probably curl.exe with the -v option.


Given all that, it made me wonder whether a site
can really track visitors, realistically, by IP.


Generally, sites track visitors by cookie, but if cookies are disabled
at the client, they'll fall back to IP address. IP tracking is not
optimal, especially since an IP address could be used by different
people at different times, or different people at the same time.


In fact,
it's not unusual in my own web logs to see commercial
GETs coming from numerous, similar IPs, even for one
page and it's related images. And it's common (I don't
know why) to see things like an IP that resolves
to Brazil in terms of geolocation load a webpage,
followed by an IP from Europe that downloads a linked
file. Yet both show the same company in a hostname
resolution.


No idea what you're trying to say there.


-chris
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