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Thread: IP addresses

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    Silver Lounger
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    IP addresses

    Didn't know where else to post this question.

    I believe each computer has its own IP address if I'm not mistaken. So if computers can be identified by their IP address how are they identified when hooked to a router like Netgear or Linksys? If I'm not mistaken both of those brands have their own IP addresses. For instance my Netgear router displays an IP address of 10.0.0.1 or 10.0.0.2 and so forth depending on which computer I am checking. I believe anyone who uses a Netgear router would also have the same IP addresses. If this is true is there some other IP address exclusive to each of my computers on my home network that would identify each of them?

    I am not talking about me running "ipconfig" to see each IP address. I'm talking about if someone wanted to trace an IP address to associate it with an individual how would that be done when hooked to a router? Is it even possible to trace one that is behind a router?

    Just as a bit of explanation for the question; some forums I've seen claim they can ban a person by identifying them using an IP address. Is this true when behind a router?

    Thanks
    H Lewton

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    Silver Lounger
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    Re: IP addresses

    At a high level, each PC that connects to a network, must be identified in some fashion. On an ethernet network, this is done with an IP Address.

    Your example of the 10.0.0.1 and .2 addresses are in the reserved area, designed for things such as home or office networks. These addresses are not accessible to the outside world (the other side of your router). Your router performs NAT services (network address translation (I believe this is the correct term)), and provides the data flow from your network to the outside. The outside has an IP Address assigned to your router that is visable to the network.

    When the forum says they can ban by an IP Address, they're banning any computer that is accessing via the external IP Address of the router (for a network), or the actual computer when only one machine is attached at a location.
    Christopher Baldrey

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    Plutonium Lounger Leif's Avatar
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    Re: IP addresses

    The IP addresses your router uses are local within your 'network' - i.e. your side of the the router.

    When you connect to the internet, you appear to be coming from an IP address that your service provider owns and can be directly traceable to them - and possibly the end user - from anywhere on the internet. You may or may not have a 'fixed' IP address given to you by your ISP, so for example you may appear to be logging into the Lounge from a different IP address each day.

    It IS possible to ban a user by blocking their IP address - we have been forced to do it here - but it is only feasible if they are the only user coming in from that IP address and they have a fixed IP address. If you were logging in from a big company or internet cafe, blocking that IP address could also block any other employees / cafe users.

    So, you can be traced by your internet IP address - your access point to the internet - but not specifically within your own network. (Not readily anyway, and not if you are running a half-decent firewall!)

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    Plutonium Lounger
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    Re: IP addresses

    To fill in a bit more of the picture, here is some more information about NAT

    Suppose you have a computer at IP Address 10.0.0.2 on your home network, and your router's external IP address is 23.45.67.89

    <UL><LI>Every internet connection has two end points.
    <LI>Each end point has an IP address and a Port number (and a few other things that we don't need to bother with here).
    <LI>When you connect to Woody's lounge your PC connects to port 80 on 68.178.254.189
    <LI>Your connection comes from a port that your PC creates, for example port 4230 on 10.0.0.2
    <LI>The NAT software on your Router changes the IP address and port in the packet to ones that it creates, for example port 5420 on 23.45.67.89, and it remembers who this connection is for
    <LI>When the lounge sends back a response to port 5420 on 23.45.67.89 the NAT software looks this up and forwards the packet to port 4230 on 10.0.0.2[/list]This enables many different computers on your home network to talk to different computers on the internet at the same time

    StuartR

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    Re: IP addresses

    Thank you all for the answers.
    H Lewton

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    Re: IP addresses

    So, you can be traced by your internet IP address - your access point to the internet - but not specifically within your own network. (Not readily anyway, and not if you are running a half-decent firewall!)

    So does this mean that they would have to ban users from an ISP or can it be traced to the individual? Or would the ISP have to identify the end user by the IP and help whoever enforce the ban?
    H Lewton

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    Plutonium Lounger Leif's Avatar
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    Re: IP addresses

    If you were consistently coming in from (e.g.) IP 123.456.789.123 that could be blocked quite easily, but it would not necessarily to know who that IP address belonged to. When you visit a website, you are basically saying 'Send me the web page to display on my computer'. As you have to give the 'return address' to send the info to, it is not that easy to browse 'anonymously', and it is relatively straightforward to identify the return address and refuse to honour the request.

    Depending on your contract with your ISP, you may or may not be coming in from the same IP number each time. It is quite common for you to be assigned an address each time you connect so there is no guarantee of consistency. In this case, it may be necessary to ban a range of IP addresses to make sure you include the individual you are trying to block. However, as I mentioned above, there is the danger you block some innocent bystander <img src=/S/smile.gif border=0 alt=smile width=15 height=15>

    To trace an IP address to an individual may be possible, but it would depend who it was registered to - and in most cases that would be the ISP. If you were getting malicious mail or a Denial of Service (DOS) attack from a specific IP address and needed to take 'legal' action, then yes, you may need to complain to the ISP to get the individual stopped.

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    Re: IP addresses

    Thank you Leif
    H Lewton

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