Different IP address on the same network

kikanot Posted messages 15 Status Member -  
kikanot Posted messages 15 Status Member -
Hello,
here's the situation: when I connect to my university's Wi-Fi network, I come across an authentication page, and once authenticated, I'm connected and everything works perfectly.

However, I need to have the same IP address on both my iPhone and my computer, so connected to the same Wi-Fi network, but the IP address is different.

Is it possible to have the same IP address between two machines on this type of Wi-Fi network?

I hope I was clear enough, thank you

Configuration: Mac OS X Snow Leopard (10.6.8) / Chrome 33.0.1750.117

11 answers

  1. brupala Posted messages 111153 Registration date   Status Member Last intervention   14 450
     
    Hi,
    If you set a static IP address, along with the right parameters, yes.
    Otherwise, no.
    Be careful, it is risky to set a static IP address on a public network.

    --
    and ... There you go!
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    1. Pierrecastor Posted messages 10830 Registration date   Status Moderator Last intervention   4 215
       
      Hello


      Be careful, it's risky to set a static IP address on a public network.


      Why is that?

      Moreover, I don't really understand the answer, we can't have two devices with the same IP on the same network, right?
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    2. brupala Posted messages 111153 Registration date   Status Member Last intervention   14 450
       
      I didn't say he could use both at the same time :-)
      I should have specified a static IP on a public network in DHCP; someone could inherit the same address as you.
      Plus the risk of attacks is greater if the same machine always has the same address on an unmanaged network.
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    3. Pierrecastor Posted messages 10830 Registration date   Status Moderator Last intervention   4 215
       
      Oh okay, I understand your response better now.
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  2. afond
     
    Hi
    you can do it, but you will have IP address conflicts, and you will probably get blocked
    I imagine that if you want to do this, it's to take advantage of internet access with only one account?
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  3. phil2k Posted messages 10841 Registration date   Status Contributor Last intervention   2 339
     
    Hello
    I still need to be on the same IP address between my iPhone and my computer
    That's not possible, it won't work.

    Why do you want the same IP address?

    Give an example of what you currently get, the IP addresses, subnet masks, and gateways of the computer and the PDA.
    --
    "To fix something that doesn't work or is too noisy, you just need to hit it with something that works better or makes more noise"
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  4. kikanot Posted messages 15 Status Member
     
    Thank you for your responses :)

    I know that normally there is an IP conflict; however, I will try to be clearer.

    First, the why and how:
    I have an application on my phone that allows me to receive my SMS on my computer, called remote messages.
    It works quite simply; you connect both your computer and phone to the same Wi-Fi network. You then open Chrome or Firefox, type the IP address and the port into the URL bar (e.g., 192.168.0.25:311), and you can see all your SMS on the computer, you can reply, etc.

    Let's take the case where there are no problems: I'm at home, I connect my computer to my router, as well as my phone. Both devices are therefore on the same network.
    For the application to work, this is essential.
    If I'm not mistaken, I am on the same address as my router (which is an IP) without having the same IP address, which explains why I do not have any address conflicts.

    The problem arises in my university, where there are two types of networks: a public network (where 90% of people are connected) and a private network with WPA2 Enterprise security.
    I have tried both networks, and in neither case can I obtain an identical "current IP" on my two machines, preventing me from using my application.

    I hope I am clearer... ? And that I am not mistaken about the case of the router?
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    1. brupala Posted messages 111153 Registration date   Status Member Last intervention   14 450
       
      If I'm not mistaken, I'm on the same address as my router (which is an IP) without having the same IP address, which explains why there's no address conflict.

      In this case, you would be confusing the public IP address (actually that of the router) and the private IP addresses, those of the machines on the local network of the NAT router.
      If that's the assumption, we are just going in circles on an unsolvable problem: retrieving the same public IP address on both machines while they are on two different internet connections.
      It would be doomed from the start; to do what you want, they must of course be on the same NAT router, in which case we are no longer talking about their own IP address, but that of the router.
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  5. phil2k Posted messages 10841 Registration date   Status Contributor Last intervention   2 339
     
    I think there is confusion.
    In any case, the 2 devices do not have the same IP address, but are on the same subnet.

    You just need to check it, by comparing the addresses on the 2 devices.
    They need to be on the same network, and therefore able to communicate.

    It should work the same way at university as at home.
    Both need to be on the same network, either public or private.

    --
    "To fix something that doesn’t work or makes too much noise, you just need to hit it with something that works better or makes more noise"
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  6. kikanot Posted messages 15 Status Member
     
    Yes, that's exactly it, the machines need to communicate, both machines are connected to the same network, I just can't get them to communicate, because in what you said, "Just check it, compare the addresses on the 2 devices.
    They must be on the same network and thus able to communicate."


    The two addresses are different at the university, but identical at home. Hence the problem, I will try to take some screenshots as soon as I have the chance to provide more information.
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    1. brupala Posted messages 111153 Registration date   Status Member Last intervention   14 450
       
      Two machines can communicate, even if they are not on the same IP network, as long as the two networks are connected by one (or more) router(s).
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  7. phil2k Posted messages 10841 Registration date   Status Contributor Last intervention   2 339
     
    check, but they are not the same at home.
    Otherwise, it wouldn't work.

    --
    "To fix something that doesn't work or makes too much noise, you just need to hit it with something that works better or makes more noise."
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  8. kikanot Posted messages 15 Status Member
     
    Well, I've just set up a Freebox as a router (not the one from home, but we'll make do with it ^^), which allows me to understand a bit more.
    Indeed, the IP address is not the same.
    I confused the DHCP IP with the router's IP, here from the Freebox.

    Overall, for everything to work, I need to have the same IP address as the box, but to avoid conflicts I need a different IP from the DHCP.
    (I hope I'm not saying anything stupid...)

    Everything is working. The computers have internet access and the application is functioning.

    The only thing left is to figure out why I can't get it to work at university.
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  9. phil2k Posted messages 10841 Registration date   Status Contributor Last intervention   2 339
     
    without giving a lesson on the IP protocol, I will try to keep it simple ... (simplistic some would say, but hey, I own it ...)

    the IP configuration of a machine consists of the IP address, the subnet mask, and the gateway address. (plus the DNS, ..)
    In DHCP, this information is provided by the DHCP server, which is, in general, the router or the box.

    For two machines to communicate on the same network, they must have the same mask, the same gateway (generally), and two different IP addresses, but within the same network, for example 192.168.0.10 and 192.168.0.11.

    At the university, you will need to gather this information on both machines: the IP address, the mask, the gateway address.

    --
    "To fix something that doesn't work or makes too much noise, you just need to hit it with something that works better or makes more noise"
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  10. flojfloj Posted messages 295 Registration date   Status Member Last intervention   91
     
    You can use a static addressing, but... There may be an IP address conflict!
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  11. kikanot Posted messages 15 Status Member
     
    Whether it's the router's address, the subnet mask, the DNS, everything is identical, except for the IP.

    So I don't understand why I can't get the two machines to communicate with each other, and there's no IP address conflict, they don't have the same one.
    Could using a network equipped with a specific security feature (WAP2 enterprise) prevent such communication?
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