Why is ip on router different to ip from www.whatismyip.com ??

Hi all,
Just wondering, how come my ip address that is shown on my router config page shows a different ip address than when i go to www.whatismyip.com ?
I'm have an ADSL connection.

Who is Participating?
hfernConnect With a Mentor Commented:
I guess from all of the above you can conclude that either:
1. somewhere in the connection from you to whatismyip.com sits a router that does network address translation. In other words, it hides youir real IP address (the one that you see on your router) from whatsmyip.com. It replaces your IP address with it's own, just like Centrepc's router, or
2. somehow there is a proxy that intercepts your http requests.

You could perhaps try another way of discovering your IP, which is by using tracert. Just do a

  tracert www.google.com

and the first address outside of your local network that you see is actually your public IP address.

Your router has 2 different ip addresses: internal ip for your lan, and external ip for internet.
Or your router just use proxy for connecting to the internet.
systemxAuthor Commented:
I know about the internal 192.x.x.x addresses.
I mean that my router shows a WAN ip address differently to www.whatismyip.com

Sorry for the confusion.

Thanks again
Worried about phishing attacks?

90% of attacks start with a phish. It’s critical that IT admins and MSSPs have the right security in place to protect their end users from these phishing attacks. Check out our latest feature brief for tips and tricks to keep your employees off a hackers line!

Perhaps your ISP put you behind a firewall..? What is the IP address that your router says it has?
Are you using a proxy? if so the proxy address is shown in the "whatismyip.com" Your isp might also be using a proxy causing this... ;)
systemxAuthor Commented:
my router says:

www.whatismyip.com says i have
May be your provider uses folowing scheme:
Internet -> ADSL Modem -> Router -> Workstation
If so, IP on whatmyip will be IP of modem, not IP of router.
You can run tracert to some site and check the host after router.

UPD: Looks like proxy, because whatismyip works on HTTP. Try to run tracert and look there.
systemxAuthor Commented:
hi again,

So I did a tracert to www.whaitismyip.com
So it goes through (my internal address for my router)
Then it goes to 58.147.*.* ( not the same as my WAN address)

So none of these address is the same as my WAN address on my router. and not the same as the address www.whatismyip.com gave me.

I'm sure the reason is very simple.
But I don't know what it is? ;)
Yes. It proves that you use a proxy to connect ot the internet. :)
Try to use http://www.leader.ru/secure/who.html instead of whatsmyip. May be leader could break through your proxy. :)
The reason is the router sets up its own internal LAN because it is splitting the IP address.  This number (usually, is it the default domain for both linksys and net gear).  is seen only internally on the network and individual addresses are assigned by the router.  This depends on how the router is set up but if you start at 100 and increment by one then every machine on the LAN will have the internal address .100, .101, etc.  You can see this internal number by running the windows program ipconfig.

The address shown on wahtismyip is the IP assigned by your ISP, held by your cable modem and is the address used by web sites when responding to any messages you send.  The router "remembers" which machine on its LAN sends a packet to a site and when a packet is returned from that site (The sender used the ISP assigned address, seen in whatismyip) the router then routes that package to the IP it assigned to the machine making the request.  This is why routers are preferred to switches and hubs.  A router has "intelligence" that maintains a table to outgoing requests and addresses.  A switch doesn't have the intelligence to remember and route the packet to a particular machine.

Being behind a WAN is the same as the being behind a router LAN but has a larger area.  The address given by whatismyip is the address seen by the "world" and any web site responding to a request.  If this address is either a proxy server or WAN, doesn't matter, a re-addressing occurs when the packet arrives at the whatismyip address to route the packet on its merry way.

If you really want to investigate this further go to internet explorer -> tools -> Internet options -> Connection -> LAN Settings.  This will show if you are using a proxy and its address.

Another way to play with this is use FireFox tools -> options -> general -> connect settings check direct connect to internet and then do whatismyip.  

Hope this helps

Scott J. Lloyd
If you are using a t1 line whatismyip reflects the serial interface of the wic card on your router, not the public usuable ip addresses assigned to you by your ISP.

your serial interface and your usable ip's can be in completely different subnets.  
You may want to a reverse DNS lookup on the IP address that www.whatismyip.com says you have and on the IP address that your router thinks you have: do a nslookup of both addresses.
Who is your ISP?
>If you are using a t1 line whatismyip reflects the serial interface of the wic card on your router, not the public usuable ip
>addresses assigned to you by your ISP.

A ridiculous and untrue statement, as verified by my own personal experience in which this is certainly *not* the case.


OK big Jon

Before you say something is rediculous do your home work.  Below is the config from my router along with whatismyip showing.  Tell me how this isn't showing the ip of my serial interface.  My usable public ip's are 65.119.19x.xx  not anything near what whatismyip showing.  You really look unprofessional when you say something is rediculous when it is the way t-1 lines are configured all the time.  

interface Serial0/0
 description 1.536 to Quest
 ip address 65.115.237.xx
 ip nat outside
 ip route-cache flow
 no fair-queue

interface Ethernet1/0
 ip address 65.119.19x.x

Your IP Is 65.115.237.xx
Copy Your IP  
Courtesy of WhatIsMyIP.com
> ip nat outside

Although you've got usable public addresses inside your router, you're hiding them all behind your T! address *as if* they were private addresses.  WhatIsMyIP.com is correctly reporting the way you've told your router to present you to the Internet; if that's not what you want, you need to fix YOUR configuration, not WhatIsMyIP.com.

So to get back to Systemx's original question... This could apply to your configuration as well. If someone along the way performs any network address translation then you would see their IP address, not the IP address of your router.. Again, probably the best way is to do a reverse DNS lookup and see who the Internet thinks owns these IP addresses. Another route would be to check with your ISP.
>OK big Jon

>Before you say something is rediculous do your home work.

Whatever - allow me to quote you (again):

>If you are using a t1 line whatismyip reflects the serial interface of the wic card on your router, not the public
>usuable ip addresses assigned to you by your ISP.

That statement, by itself, is BS - you didn't say you were using NAT, and to claim your statement as true in every case is indeed ridiculous.  Most T1 connections are terminated on a router that routes (hence the name) packets destined to a particular network on to those hosts (or a firewall protecting those hosts).  It typically does not run NAT, unless you are using it as a firewall (in which case you need to say "firewall" or "firewall/router", not "router").

>You really look unprofessional when you say something is rediculous when it is the way t-1 lines are configured all
>the time.  

You really look unprofessional by suggesting that this is a typical scenario (it's not), by not mentioning NAT in the first place, and then trying to take me to task for omissions on your own post.

Do your own homework.


systemxAuthor Commented:
Thanks for the interesting disscussion, its good to see people that are passionate about technology. My question was why is my WAN ip address shown on my router different to the ip address from whatismyip.com (i assume that it's my public ip).

Here's a test i did:
I tried forwarding port 80 to my computer with IIS installed and accessing the ip's to see which one would get to my computer's website. (from another connection/phone line completely seperate from the network)

The WAN ip address from my router seems to be the one that gets to my computer. The one from whatismyip.com does nothing.

My question is why is this?
I have a strong feeling that my connection uses a proxy as suggested by some of you above.

Okay I must confess, the main reason for my asking this question is so that I can use bittorrent. I have used bittorrent before and know how to configure it. But this is a new connection I just had installed last week and I just can't get it to work. Port forwarding is fine it connects to many peers etc. but it won't download anything. So I figured there was something strange about the ip addresses from whatismyip.com and the WAN ip from my router and I want to know why and maybe a way to get around this problem.

I think it's time I put the points up a bit, seems to be getting complicated.

Thanks for the help
systemxAuthor Commented:
Just found out, my isp uses a proxy, and they filter just about everything. So bittorrent won't go through. How can they know it's bittorrent anyways? Even though I change the ports and everything..
They said I have to upgrade (pay more) my connection if I wan't to use bittorrent. 0_0
Well, nevermind. That's a different question alltogether.

Thanks for the disscussion.
You may want to see if you can find another ISP that does not play such games. Thanks and good luck!
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.