Is it possible to have the same IP Address as someone else?

Discussion in 'Community Discussion' started by (StationOfPlay), Mar 15, 2008.

  1. (StationOfPlay) macrumors newbie

    Joined:
    Jan 13, 2008
  2. abijnk macrumors 68040

    abijnk

    Joined:
    Oct 15, 2007
    Location:
    Los Angeles, CA
    #2
    Not really. It would defeat the purpose of having an IP address to begin with. It would be like having the same Social Security address as someone else here in the US. Not really practical, and not really part of the design. You can research it on your own, it will take all of two seconds (actually .06 seconds according to Google ;)), but for the sake of giving you a link, here is the wiki: http://en.wikipedia.org/wiki/IP_address

    EDIT: I realize that I might be taking your question a little too literally. You might end up with the same IP address as someone else in the world, but when it comes to explaining it I don't think I could do a good job. :) I would suggest reading through the wiki page to get a general idea of how IPs work.
     
  3. (StationOfPlay) thread starter macrumors newbie

    Joined:
    Jan 13, 2008
    #3
    Dangit. I got banned from this one forum because apperently i had alternate accounts. I wanna prove to the mod that i'm not this other member because I"M NOT.:mad:
    It's driving me crazy. How can i prove to them that i'm not that member?
     
  4. abijnk macrumors 68040

    abijnk

    Joined:
    Oct 15, 2007
    Location:
    Los Angeles, CA
    #4
    Well then perhaps this wiki page is more to your liking: http://en.wikipedia.org/wiki/IP_address_spoofing
     
  5. zioxide macrumors 603

    zioxide

    Joined:
    Dec 11, 2006
    #5
    Not at the same time, but if your ISP uses dynamic IPs you definitely get IPs that other people have used.
     
  6. yg17 macrumors G5

    yg17

    Joined:
    Aug 1, 2004
    Location:
    St. Louis, MO
    #6
    Who is your ISP? I know a couple like to use proxies which would effectively make multiple people look like they have the same IP (they really don't though).

    Also, they may have banned the IP block. For example, if your IP address is 1.2.3.4, they may have banned 1.2.3.0 thru 1.2.3.254 (because even if someone has a dynamic IP from their ISP, chances are, no matter what IP they get will be within that same IP block).

    As far as the original question at hand, no, it's not possible (with the exception of proxies, where you still have a unique IP but it doesn't appear that way, and private IP addresses).

    And in regards to IP spoofing, while it is possible, it's really only good for one way traffic from your computer to some other host on the internet. You can spoof with DDOSes because you're just blasting out packets to something else and don't care where the response goes. But with 2 way traffic, like HTTP, you can't spoof. You'll send a request for the webpage, and in that TCP packet that gets sent, you have a spoofed IP as the sender. The server will respond with the page to that sender IP in the packet. But since that IP isn't yours, you won't get the data back. It will be routed somewhere else, depending on who actually owns that IP you spoofed. It would be like putting some address other than your own as the return address of a letter you send in the mail. The recipient will respond to that address, and you'll never get that response since it went to someone else.
     
  7. Baron58 macrumors 6502

    Joined:
    Feb 19, 2004
    #7


    On the same network at the same time, no. Never.

    There are IP addresses that are part of the internet world-wide, and are 100% unique. For example, the IP address that your ISP gives on your cable connection. If you connect your computer directly to your cable modem (NO ROUTER in between), then you will be assigned a public IP address. Now let's say you shut down your machine for a week (e.g. you go on vacation). IP addresses that are dynamically assigned are 'recycled'. Since your IP address is not being used, it goes back into the pool to be assigned to somebody else. When you come back from vacation and start up your computer, then it gets assigned another available IP address from the pool. This means that you CAN have multiple IP addresses at different times in this situation, including of course one that has been 'somebody elses' at some previous time. However, you can't have the same IP address as somebody else at the same time.


    There is another situation that doesn't apply to what you're asking for, but just so you understand.....

    The description ABOVE can be shown like this:
    (your computer with public IP address) --> Internet


    The description BELOW can be shown like this:
    (your computer and others in your house/office with private IP addresss) --> (router with public IP) --> Internet

    Notice that the router is in the middle. The router has ONE public IP address (from your ISP), and assigns many "private" IP addresses to devices on the "inside" of your home/office network. These addresses are usually 192.168.x.x, or 10.x.x.x, or 172.x.x.x, and can NEVER be used on the public internet. The router translates the public address on the inside to the one private address visible to the outside. To other computers on the outside it looks like a lot of traffic coming from the one public address. The other computers on the inside of your network are masquerading behind the one public address. So, at home your computer may have an address of 192.168.1.100, and your friend next door (who also has a router) may also have an address of 192.168.1.100, so while you technically have the "same" address as somebody else, that fact is never seen outside of your private home network and his private home network. Publicly, what is seen is your public address, and his public address.
     
  8. Gelfin macrumors 68020

    Gelfin

    Joined:
    Sep 18, 2001
    Location:
    Denver, CO
    #8
    At the same time? Not unless something is misconfigured badly, and your network connection would not work properly so long as the conflict existed. It would be like two houses having the same telephone number. How would the phone switching system know whose house to ring? However, IP addresses are a finite resource, and ISPs do reassign them. You'll occasionally find yourself in a situation where the former owner of an address did something to annoy someone on some service you'd also like to use.

    If your ISP assigns you a dynamic IP address, then there are circumstances under which your address may be reassigned automatically, though there are usually some measures in place to try to assign you the same address every time. If you're behind a NAT router, then all nodes on your local network may appear with a single public IP address.

    Because of this sort of thing, sites really should not use IP addresses as an absolutely reliable indicator of identity. Common IP address can be a good indication, or confirmation, of a sock puppet or ban-skirting account, but setting up a system to automatically reject two registrations coming from a single IP address is a bad idea. An IP ban should be considered a "nuke the site from orbit" approach, to be reserved for particularly bad or prolific offenders who are otherwise wasting administrators' time swatting problems one at a time.

    On the other hand, don't take this as an accusation, because I know nothing of your situation, but on the off chance you aren't telling us the whole story here, don't try to play this card against a human who has made a conscious decision that two accounts belong to the same user. Same IP address is usually just a very big coffin-nail among several others. Trying to get an account reinstated through legalistic parsing games and claiming the admin cannot know something with absolute certainty is just going to infuriate him and make it far less likely you'll ever get access. People doing weaselly things are always way more obvious than they think they are, and playing games about it just insults people's intelligence.
     
  9. (StationOfPlay) thread starter macrumors newbie

    Joined:
    Jan 13, 2008
  10. Rodimus Prime macrumors G4

    Rodimus Prime

    Joined:
    Oct 9, 2006
    #10

    you IP address is dynamic. It changes from time to time. Now it is possible remotely possible that some one that forum happened to be assigned the same IP address as you had previously.

    I gone 6-7 months straight with the same dynamic ip address. Then they decided to change it on me.
     
  11. MacNut macrumors Core

    MacNut

    Joined:
    Jan 4, 2002
    Location:
    CT
    #11
    Doesn't a cable modem have the same IP no matter what?
     
  12. yg17 macrumors G5

    yg17

    Joined:
    Aug 1, 2004
    Location:
    St. Louis, MO
    #12
    Not unless you're paying for a static IP. IPs on cable connections can change (they don't change often, but they can indeed change)
     
  13. MacNut macrumors Core

    MacNut

    Joined:
    Jan 4, 2002
    Location:
    CT
    #13
    Ok so MacRumors will ban someone via IP address. If it is a dynamic IP how can they track who they are banning if the IPs are always changing.
     
  14. Rocksaurus macrumors 6502a

    Rocksaurus

    Joined:
    Sep 14, 2003
    Location:
    California
    #14
    Though the odds are low, you may also want to make sure that someone else isn't hopping aboard your wireless network (if you have one) for a free ride.

    Also, if you're being banned by ip and are on a dynamic ip, then eventually you will be unbanned (due to your ip changing) - unless they're banning a range, in which case they have no right to ban you in the first place. :)
     
  15. yg17 macrumors G5

    yg17

    Joined:
    Aug 1, 2004
    Location:
    St. Louis, MO
    #15

    You can't. Which is why IP bans are usually an absolute last resort for most forum administrators. But even with an IP ban, it's still a one in a million chance another member will have that IP.

    Fortunately, with the widespread use of broadband, where IPs tend to change far less frequently, you can be a bit more sure you're not going to have any innocent casualties of war. It's not like dial up where your IP changed every time you dialed in. But still, it should be a last resort.
     
  16. sushi Moderator emeritus

    sushi

    Joined:
    Jul 19, 2002
    Location:
    キャンプスワ&#
  17. yg17 macrumors G5

    yg17

    Joined:
    Aug 1, 2004
    Location:
    St. Louis, MO
    #17
    Yes, but while IPs can be spoofed, 2 way traffic is pretty much impossible with a spoofed IP. I explained the reasonings behind that in an earlier post in this thread.

    And MACs only matter within your local network. Every time a packet makes a hop through a router, the router replaces the source MAC address with its own MAC address and the destination MAC address with the one of the next hop router, so you can spoof someone else's MAC, but for internet traffic, it really won't change a thing since your router ends up replacing both MACs in the packet.
     
  18. Melrose macrumors 604

    Melrose

    Joined:
    Dec 12, 2007
    #18
    This. I learned the hard way about this when I was setting up IP restrictions on a client site so they could log in. Poor guy got more and more irritated every day because I'd allow his IP, then he'd come on in a day or so and be locked out again.
     
  19. Grey Beard macrumors 65816

    Grey Beard

    Joined:
    Sep 10, 2005
    Location:
    The Antipodes.
    #19
    Hey Melrose, Do you realise that this is a four year old thread that was resurrected by a spammer?

    KGB:rolleyes:
     
  20. Melrose macrumors 604

    Melrose

    Joined:
    Dec 12, 2007
    #20
    I did not. Thank you kid sir.

    Damn spammers. *coughs on old thread dust*
     

Share This Page