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private WAN IP

New Poster

private WAN IP

Hello,

Can Comcast assign private (non public) IP address to my modem?

I have non business, residentual account.

 

Chatted twice with help desc in vain: they gave me security department number, which seems to be abandoned (waited twice for 40 mins).

 

Would appreciate any help on this matter.

 

Thanks!

Expert

Re: private WAN IP

Can you be a bit more clear? You already have a private WAN IP going to your modem, hence you are on the internet. Are you saying you would like an additional IP Address?


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Expert

Re: private WAN IP


@jweaver0312 wrote:

Can you be a bit more clear? You already have a private WAN IP going to your modem, hence you are on the internet. Are you saying you would like an additional IP Address?


The WAN IP address that the modem bridges to the LAN is public.



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Expert

Re: private WAN IP


@sadman wrote:

Hello,

Can Comcast assign private (non public) IP address to my modem?

I have non business, residentual account.

 

Chatted twice with help desc in vain: they gave me security department number, which seems to be abandoned (waited twice for 40 mins).

 

Would appreciate any help on this matter.

 

Thanks!


No, sorry. 



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New Poster

Re: private WAN IP

Nope, the IP I have is public in IANA terms, i.e. it does not belong to any of the following ranges:

 

Class Starting IP Address Ending IP Address # of Hosts
A 10.0.0.0 10.255.255.255 16,777,216
B 172.16.0.0 172.31.255.255 1,048,576
C 192.168.0.0 192.168.255.255 65,536

 

I want an IP that would be from one of these classes, presumably from 10.x.x.x.

Expert

Re: private WAN IP

You can't get that on a residential connection. You can't even get those ranges on a Business Class connection. You would get a block of statically assigned addresses of their discretion.



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Expert

Re: private WAN IP


@sadman wrote:

Nope, the IP I have is public in IANA terms, i.e. it does not belong to any of the following ranges:

 

Class Starting IP Address Ending IP Address # of Hosts
A 10.0.0.0 10.255.255.255 16,777,216
B 172.16.0.0 172.31.255.255 1,048,576
C 192.168.0.0 192.168.255.255 65,536

 

I want an IP that would be from one of these classes, presumably from 10.x.x.x.


You can't have both a physical presence on the public internet and have a private IP address.

 

Those IP address ranges were specifically set aside because it was understood early on that:

 

  1. The IP system (now called IPv4) at some point will run out of unique numbers to assign to every computer on the internet, and
  2. A lot of users didn't necessarily need nor want their devices to be publicly exposed.

They're designed to be internal, private addresses only. 

 

 


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New Poster

Re: private WAN IP

I belong to category #2 but it looks like I can't exercise this option with Comcast, unfortunately.

Expert

Re: private WAN IP


@sadman wrote:

I belong to category #2 but it looks like I can't exercise this option with Comcast, unfortunately.




That's part of why NAT translation was designed. To hide your network clients behind private IP addys. It also helps with the depletion of IPv4 addresses. You have a router, you have NAT. 



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New Poster

Re: private WAN IP


@EG wrote:




You have a router, you have NAT. 


That's true.

I expect it would be better from security point of view to have WAN interface of my router itself is NAT'ed.

Regular Contributor

Re: private WAN IP

Maybe I don't understand you, but if you requested a web page, and the server received a private address, then the web page would be sent - nowhere - right?  Because the address the server received would only be resolvable within its own subnet.  Ie: your 10.x.x.x is not the same 10.x.x.x that the server could see.

 

It is possible to NAT the WAN side of a router - by putting it behind another NAT router (though double NAT can cause issues with some protocals) however, even if you did that and then went to some web page that displays your IP, you would still see the public IP address of the outer router.

Expert

Re: private WAN IP


@sadman wrote:

@EG wrote:




You have a router, you have NAT. 


That's true.

I expect it would be better from security point of view to have WAN interface of my router itself is NAT'ed.


FWIW, you are overthinking this unnecessarily.



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Expert

Re: private WAN IP


@strega7 wrote:

Maybe I don't understand you, but if you requested a web page, and the server received a private address, then the web page would be sent - nowhere - right? 


A private IP addy couldn't be internet routable to a remote web server in the first place.



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Regular Contributor

Re: private WAN IP

Agreed.  I thought the OP was suggesting that Comcast could change something in their (and possibly everyone else's!) routers to send private addresses.  And I was just saying even if they did that, there would still be a problem. Basically we're both saying that routing a non-routable address doesn't make a lot of sense. Smiley Happy

New Poster

Re: private WAN IP


@EG wrote:


FWIW, you are overthinking this unnecessarily.


There is no limits for paranoya Smiley Happy

Expert

Re: private WAN IP

😀😎


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Expert

Re: private WAN IP

strega7 wrote;

"Basically we're both saying that routing a non-routable address doesn't make a lot of sense. "

No. I'm saying that it is impossible.


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Regular Contributor

Re: private WAN IP

Oh, I could write that code, but whatever adjective you prefer is fine.

 

Expert

Re: private WAN IP

Seriously ??? You're going to change / re-write the IANA protocols ? 😀


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Highlighted
Regular Contributor

Re: private WAN IP

Sure - it's just software that needs to be rewritten in my mind for a thought experiment. And imagining software that doesn't completely work anyway (ie: request goes out but response doesn't come back, like I said it wouldn't in my first post) is all the easier to imagine writing.