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Private IP addresses Cablevision



 
 
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  #1  
Old September 9th 04, 03:27 AM
myname
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Posts: n/a
Default Private IP addresses Cablevision

Hi,

I recently switched to optimum online from DSL. My Linksys router was
configured with a static private IP address on the public interface
(192.168.x.x). After connecting the router to the cable modem, I was
able to browse without any problem. I then changed the configuration
on the router from static to DHCP client and got a public IP address.
What I dont understand is how did I connect the Internet with a
private IP address?

I would appreciate if anyone can help me solve this mystry.

Thanks in advance

Philip
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  #3  
Old September 9th 04, 07:15 AM
Quaoar
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Default


"myname" wrote in message
om...
Hi,

I recently switched to optimum online from DSL. My Linksys router was
configured with a static private IP address on the public interface
(192.168.x.x). After connecting the router to the cable modem, I was
able to browse without any problem. I then changed the configuration
on the router from static to DHCP client and got a public IP address.
What I dont understand is how did I connect the Internet with a
private IP address?

I would appreciate if anyone can help me solve this mystry.

Thanks in advance

Philip


The router Device IP Address on the Setup page is only applicable to the
LAN side. Your DSL ISP issued a WAN IP address that was not in the
private 192.168.X.Y range. A private address on a public network is
meaningless (by definition) since many might choose the same IP address
as you, bringing the Internet to its knees. You can set the routers LAN
address to whatever you choose, the WAN doesn't use it and doesn't care
what it is. On the WAN side many cable companies register only the MAC
address of the router and assign an IP address to it on their system,
there is no ability to specify the WAN IP address from the router in
gateway mode (connected to the Internet). Even if you contract a
business-class static IP address, the static IP address is assigned by
the ISP, neither you nor the router has any control over it. The DHCP
toggle in the router's DHCP page is its own server to the LAN only. If
you were running only static LAN IP addresses, you could turn this off.


Q


  #4  
Old September 9th 04, 07:43 AM
Warren
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Posts: n/a
Default

Quaoar wrote:

The router Device IP Address on the Setup page is only applicable to
the LAN side.


Unless they've changed it in later firmware from what I have in v1.39,
you can specify both the LAN side and the WAN side IP on the Setup page.

Your DSL ISP issued a WAN IP address that was not in the private
192.168.X.Y range.


If he did in fact specify a WAN IP address, this would not happen.

A private address on a public network is meaningless (by definition)
since many might choose the same IP address as you, bringing the
Internet to its knees.


Well, not meaningless. A private IP address just isn't routable. It only
would have an adverse effect if another device downstream from the first
router encountered was using that address. Devices with non-routable IP
addresses will not be able to communicate beyond that router.

You can set the routers LAN address to whatever you choose, the WAN
doesn't use it and doesn't care what it is.


But he says he's not talking about the LAN IP. He said he set a static
IP on the WAN side.

On the WAN side many cable companies register only the MAC address of
the router and assign an IP address to it on their system,


Irrelevant to this situation. Provisioning is not the issue.

there is no ability to specify the WAN IP address from the router in
gateway mode (connected to the Internet).


Yes. You can specify the WAN IP address.

Even if you contract a business-class static IP address, the static IP
address is assigned by the ISP, neither you nor the router has any
control over it.


If the ISP assigned him a static IP, he would manually enter it on the
Setup page of the router. He wouldn't have control over what the ISP
tells him it will be, but he does have control over typing it in
correctly.


The DHCP toggle in the router's DHCP page is its own server to the LAN
only. If you were running only static LAN IP addresses, you could
turn this off.


That is true. The DHCP tab controls only the LAN IP address.

To turn off DHCP on the WAN side, one toggles from "Obtain an IP Address
Automatically" to "Specify an IP Address" on the setup page.

I suspect that what happened was the OP was actually looking only at the
DHCP tab, which only controls the LAN side, and not at the Setup tab.
When you specify a WAN IP address on the Setup tab, you also need to
specify the subnet mask, the default gateway, and at least one DNS
server. The OP may have done this, or it may be a significant clue that
he didn't mention these settings, leading to the conclusion that he was
really playing with the LAN IP address, not the WAN IP address.

--
Warren H.

==========
Disclaimer: My views reflect those of myself, and not my
employer, my friends, nor (as she often tells me) my wife.
Any resemblance to the views of anybody living or dead is
coincidental. No animals were hurt in the writing of this
response -- unless you count my dog who desperately wants
to go outside now.
Blatant Plug: Cooking with Intense Heat
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  #5  
Old September 9th 04, 10:32 PM
NormanM
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Default

In article , Quaoar says...

The router Device IP Address on the Setup page is only applicable to the
LAN side. Your DSL ISP issued a WAN IP address that was not in the
private 192.168.X.Y range.


Linksys BEFSR11, Firmware Version: 1.46.00, Jun 24 2004. On my
setup page I can set the LAN IP address, and I can choose among several
options for the WAN IP address; one of those options is: Static IP. Would
you know how to configure that IP address? (I used that option on an SMC
Barricade, and set the WAN IP address to an RFC 1918 IP address, once. It
worked, too.)

A private address on a public network is
meaningless (by definition) since many might choose the same IP address
as you, bringing the Internet to its knees.


Actually, the Internet would never notice an RFC 1918 IP address was even
being used. The first router which handles publicly routed packets would
just ignore an IP address for which no routing is announced. (This includes
bogons, and some IANA assigned IP addresses whose owners don't announce
public routes.)

You can set the routers LAN address to whatever you choose, the WAN
doesn't use it and doesn't care what it is.


My Linksys BEFSR11 is currently using 192.168.102.2 on the WAN. It does use
this RFC 1918 address, and it does care what it is.

On the WAN side many cable companies register only the MAC
address of the router and assign an IP address to it on their system,
there is no ability to specify the WAN IP address from the router in
gateway mode (connected to the Internet).


While it is true that some cable companies use MAC registration, that seems
to be declining. And it is entirely possible to manually specify an RFC 1918
IP address on the WAN port of most routers; I did it with my SMC Barricade
7004BR. Of course, if your ISP is providing an IP address by DHCP lease, or
MAC registration, or DOCSIS certificate registration (is that how the cable
companies that don't use MAC do it now?), and you pick your own IP address
out of thin air, you won't get onto the Internet.

Even if you contract a business-class static IP address, the static IP
address is assigned by the ISP, neither you nor the router has any control
over it.


Of course. If you are buying Internet service from a provider, you must
accept their IP address.

The DHCP toggle in the router's DHCP page is its own server to the LAN only.
If you were running only static LAN IP addresses, you could turn this off.


There are other arrangements, as well. My LAN uses DHCP assignment from a
Netgear FR114P. I can make an alternate dial-up connection over a modem
attached to an SMC Barricade 7004BR. The Barricade has DHCP turned off, and
is hard set to 192.168.102.3. The Netgear has a MAC reservation for the
Barricade on 192.168.102.3.

--
Norman
~Win dain a lotica, En vai tu ri, Si lo ta
~Fin dein a loluca, En dragu a sei lain
~Vi fa-ru les shutai am, En riga-lint
  #6  
Old September 9th 04, 10:43 PM
NormanM
external usenet poster
 
Posts: n/a
Default

In article , myname says...

I recently switched to optimum online from DSL. My Linksys router was
configured with a static private IP address on the public interface
(192.168.x.x). After connecting the router to the cable modem, I was
able to browse without any problem. I then changed the configuration
on the router from static to DHCP client and got a public IP address.
What I dont understand is how did I connect the Internet with a
private IP address?


I would appreciate if anyone can help me solve this mystry.


I wish I could understand what you described, but it is clear as mud.
In general, ISPs issues IP addresses from their IANA assigned public IP
address pool. However some ISPs actually use an internal NAT system,
assigning RFC 1918 IP addresses to their customers, and connecting those
customers to the Internet through an ISP run NAT router.

The part of your description which puzzles me is that you claim to have
changed your WAN IP address, and still gotten onto the Internet. As another
poster has mentioned, your Internet connection is under the control of your
ISP; they control the IP address you are assigned for Internet connection.

Frankly, if your DSL provider was using a static RFC 1918 IP address, and
your cable company is using a DHCP public IP address, your rig should not
have worked at all until you made the requisite change in your router.

WAN is a confusing term. Strictly speaking, it means "Wide Area Network",
and refers to a network of larger scope than a LAN ("Local Area Network").
While the Internet is a WAN within the definition of the term, there can be
networks intermediary to the Internet, and your LAN, which can be considered
a WAN. You encountered such an arrangement with your DSL provider. I have
created such an arrangement within my home; though WAN is usually applied to
a network which spans multiple premises.

--
Norman
~Win dain a lotica, En vai tu ri, Si lo ta
~Fin dein a loluca, En dragu a sei lain
~Vi fa-ru les shutai am, En riga-lint
  #7  
Old September 9th 04, 10:59 PM
James Knott
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Posts: n/a
Default

NormanM wrote:

In general, ISPs issues IP addresses from their IANA assigned public IP
address pool. However some ISPs actually use an internal NAT system,
assigning RFC 1918 IP addresses to their customers, and connecting those
customers to the Internet through an ISP run NAT router.


Some ISPs also use RFC1918 addresses for internal routing of public
addresses.

--

(This space intentionally left blank)
  #8  
Old September 10th 04, 05:39 AM
NormanM
external usenet poster
 
Posts: n/a
Default

In article le.rogers.com,
James Knott says...

NormanM wrote:


In general, ISPs issues IP addresses from their IANA assigned public IP
address pool. However some ISPs actually use an internal NAT system,
assigning RFC 1918 IP addresses to their customers, and connecting those
customers to the Internet through an ISP run NAT router.


Some ISPs also use RFC1918 addresses for internal routing of public
addresses.


That concept seems to be a bit fuzzy to me. Perhaps you could offer an
example?

--
Norman
~Win dain a lotica, En vai tu ri, Si lo ta
~Fin dein a loluca, En dragu a sei lain
~Vi fa-ru les shutai am, En riga-lint
  #9  
Old September 10th 04, 03:24 PM
James Knott
external usenet poster
 
Posts: n/a
Default

NormanM wrote:

In article
le.rogers.com, James
Knott says...

NormanM wrote:


In general, ISPs issues IP addresses from their IANA assigned public IP
address pool. However some ISPs actually use an internal NAT system,
assigning RFC 1918 IP addresses to their customers, and connecting
those customers to the Internet through an ISP run NAT router.


Some ISPs also use RFC1918 addresses for internal routing of public
addresses.


That concept seems to be a bit fuzzy to me. Perhaps you could offer an
example?


Here's one. In this example, the second hop is my ISP @ 10.45.232.1,
between me and their nearest office, which is listed as the 3rd hop at
66.185.93.65. Passing through the RFC1918 addresses does not cause a
problem, so long as it's use is with the ISPs internal network, in that
there should not be any traffic to those addresses from the customer.
The 1st hop, is my linux firewall @ 192.168.1.1.

traceroute to www.yahoo.com (216.109.118.72), 30 hops max, 40 byte packets
1 firewall.home (192.168.1.1) 0.798 ms 0.494 ms 0.531 ms
2 10.45.232.1 8.074 ms 10.239 ms 13.006 ms
3 gw03-vlan201.wlfdle.phub.net.cable.rogers.com (66.185.90.161) 19.090 ms
17.230 ms 32.273 ms
4 gw01-vlan961.wlfdle.phub.net.cable.rogers.com (66.185.93.65) 7.077 ms
10.930 ms 11.950 ms
5 gw02.wlfdle.phub.net.cable.rogers.com (66.185.80.130) 14.937 ms
14.999 ms 6.112 ms
6 igw01.ny8th.phub.net.cable.rogers.com (66.185.81.13) 31.996 ms 34.491
ms 39.881 ms
7 * * *
8 vl812.bas1-m.dce.yahoo.com (216.115.98.105) 41.644 ms 45.267 ms
42.918 ms
9 vlan220-msr2.dcn.yahoo.com (216.115.96.165) 41.142 ms 41.656 ms
39.813 ms
10 UNKNOWN-216-109-120-207.yahoo.com (216.109.120.207) 41.631 ms
vl32.bas1-m.dcn.yahoo.com (216.109.120.150) 40.042 ms 41.675 ms
11 p9.www.dcn.yahoo.com (216.109.118.72) 40.506 ms 43.528 ms 41.652 ms




--

(This space intentionally left blank)
  #10  
Old September 12th 04, 08:08 AM
NormanM
external usenet poster
 
Posts: n/a
Default

In article om, James
Knott says...

NormanM wrote:


In article
le.rogers.com, James
Knott says...


NormanM wrote:


In general, ISPs issues IP addresses from their IANA assigned public IP
address pool. However some ISPs actually use an internal NAT system,
assigning RFC 1918 IP addresses to their customers, and connecting
those customers to the Internet through an ISP run NAT router.


Some ISPs also use RFC1918 addresses for internal routing of public
addresses.


That concept seems to be a bit fuzzy to me. Perhaps you could offer an
example?


Here's one. In this example, the second hop is my ISP @ 10.45.232.1,
between me and their nearest office, which is listed as the 3rd hop at
66.185.93.65. Passing through the RFC1918 addresses does not cause a
problem, so long as it's use is with the ISPs internal network, in that
there should not be any traffic to those addresses from the customer.
The 1st hop, is my linux firewall @ 192.168.1.1.


trace snipped

Ah, I get it. They aren't exactly "routing public IP addresses through RFC
1918 IP addresses. They are using internal routes between your computer and
the Internet. It appears that your 2nd hop router is a bridge; your cable
modem, perhaps?

--
Norman
~Win dain a lotica, En vai tu ri, Si lo ta
~Fin dein a loluca, En dragu a sei lain
~Vi fa-ru les shutai am, En riga-lint
 




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