Computer ISP address -- how to find it out and is it possible to change it???

Discussion in 'Computers' started by Allan, Feb 28, 2004.

  1. Allan

    Allan Stunt Coordinator

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    Hi, I was wondering how to find out my computer's ISP address. Also, would it be possible to change it? I have a laptop and a desktop and get the internet through an ethernet connection. I want to set up a wireless intranet but the ethernet connection is specifically set to only work on my desktop. I was wondering if I could change my laptop's ISP to match my desktops and therefore have both computers work on the same ethernet line.

    Make sense? Any advice would be truly welcome!

    Thanks,
    Allan
     
  2. Bill Cowmeadow

    Bill Cowmeadow Second Unit

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    Start
    Run
    dosprmpt

    When the dos window opens, at the prompt type

    ipconfig

    You probably can't do it the way you want to, but if you can get XP pro, you can share the connection with whatever you want.
     
  3. Keith Mickunas

    Keith Mickunas Cinematographer

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    Do both computers talk to the internet and each other, or is that what you're trying to accomplish? You really need to provide a lot more details. What is your ISP? How are you connected? Is this a cable modem or DSL? Is it DHCP?

    Assuming you're on cable or DSL, and you're using DHCP, it should be fairly simple to achieve what you want. You'll need a combo wireless access point (WAP) and Cable/DSL router. Linksys, DLink, Netgear, and many others make these devices and they are widely available wherever you buy computer stuff. You'll connect your cable or dsl device to the WAP's internet port, and your desktop PC to one of the regular ethernet ports on the WAP. Then from your PC, following the instructions for the WAP, you connect to the WAP and configure it to talk to your ISP and distribute the internet connection to your PC and wireless devices.

    These devices are made for this specific purpose, so the instructions should be easy enough to follow and get you going. They also act as a firewall which is nice to have when you're running windows.
     
  4. Allan

    Allan Stunt Coordinator

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    Well, here is the situation... I have an ethernet connection (not a modem and not DSL). It is provided by the university in which my wife attends. Anyway, when we had the ethernet connection set up by the school, they said that only one computer could be configured to work with the connection. (They had to come and do something to the computer to make it work with the connection.) I recently bought a new laptop and want it to work as well. I tested it first by simply plugging the ethernet wire from the wall into the laptop, but it didn't work. The final plan is to create a wireless intranet in my apt. I know that I will need a router to do that, but the first step seems to be to get my laptop to work with the ethernet connection. So, I am thinking that if I can change the ISP address of my laptop to match the address of my desktop, maybe I can "trick" the ethernet connection into thinking both computers are the same and thus allo both to work with the connection. (I am not that great with computers, so if this makes absolutely no sense, I apologize.)

    So, is there a way to accomplish what I want to do????

    Thanks so much,
    allan
     
  5. Steve Berger

    Steve Berger Supporting Actor

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    Well --- first a little terminology ; an ISP is someone who supplies your internet access , the University in this case. An IP address is a unique identifier for a given computer. They can be supplied in various ways by the ISP , dynamic (changeable)is the most common but schools usually give you a fixed IP address and you will have to determine what it is. Since is is unique only one PC can use it at a time. A router would use that IP address for itself and assign translated addresses for the computers connected to it (the router).

    Winipcfg would tell you what address has been assigned , along with other information . These numbers would need to be entered to configure your network settings. While this is fairly (?) simple for Win98 it can be harder to do under other operating systems.

    The easiest way , if it is allowed , would be to ask them to set up your wireless router/access point. (ask before you buy it in case they say no , but there is usually a work-around). There could be other issues , like firewalls and passwords. Finding someone who is familiar with the system in use might be a solution also.(and a good idea)

    Setting up wireless access would seem to be a legitimate use of your network connection while multiple computers might be considered abuse. (under some school policies) Although they might be paranoid about someone breaking in on an unsecured wireless link. You might want to ask around before doing something that might cause them to revoke your connection.
     
  6. Keith Mickunas

    Keith Mickunas Cinematographer

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    Allan, this connection can probably be set up in the same way as a cable modem or DSL line. The cable modem or DSL modem has an ethernet connection and just makes it appear that the user's computer is on a LAN. You are effectively on a LAN.

    The connection is going to be either a static IP, or a dynamic IP (DHCP). We have to determine that first. I've got machines running Windows XP only, I don't have earlier versions and you haven't said what you run so that makes figuring it out a bit more difficult.

    First, find Network Connections (look in Control Panel or right click on Network Neighborhood or My Network Places and choose properties). There are various places to do this, in explorer, on the desktop, etc. You'll have to poke around a bit, it will vary depending on your version of Windows.

    Look for Local Area Connection or something similar to that.
    Right click on it and bring up properties. You should get a dialog with a few tabs on the top, a line describing the hardware (model of the network card). Under that will be a box that says
    "This connection uses the following item:"
    Inside that box you should see a few drivers listed, likely the following:
    Client for Microsoft Networks
    File and Printer Sharing for Microsoft Networks
    Internet Protocol (TCP/IP)

    Double click Internet Protocol (TCP/IP)
    That'll bring up a dialog for the properties.

    If "Obtain an IP address automatically" is selected, you're using DHCP. If it's not, you'll see all the numbers filled in for IP, subnet, gateway, etc. That's called a static connection.

    If it's DHCP, the solution may be fairly straight-forward. You get a router, configure it so it gets the internet or WAN ports address via DHCP. Just follow the manual like you have cable or DSL. Then you tell the router to allow DHCP on the local network (your computers). Configure your laptop to get it's IP address automatically (similar steps as the desktop), plug the router into the school's port, plug your PC to the router, and reboot the computers and all should be well.

    If it's static right down all the numbers in the properties dialog. Then you configure the router with those numbers for the internet connection. I'd recommend you go ahead configure the router to allow DHCP as I mentioned in the previous paragraph and change your desktop over to DHCP.

    The manual for the router will likely cover all this. They're made for people who don't know a lot about networking. It can probably guide you through most versions of windows ok.
     
  7. Keith Mickunas

    Keith Mickunas Cinematographer

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    Allan, I found a simple way to determine some of this. Open up a DOS command prompt and run "ipconfig /all". Look for a line that says Dhcp Enabled. . . . . .
    It'll say yes or no, if it's yes, then you're connected via DHCP. If not, write down all the numbers from there to use in your router.
     
  8. SethH

    SethH Cinematographer

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    If your wife's university is like mine you're out of luck. I'm in an apartment at college that has ethernet provided by a third-party group that has a monopoly and likes to screw people over. Here the ports read the MAC address of the computer attached to the port and will only work with that MAC address. The only way to get around it (if you're in the same situation) is to hook a router to the port and then ask the company to reset the port for your "new computer" (being the router).

    The company I have to have ethernet through does not allow multiple computers nor does it allow LAN's, wired or wireless. I have $200 of wireless equipment sitting in my closet that I bought while in another apartment, but I can't use it. I'm bitter . . . very bitter.
     
  9. Andrew W

    Andrew W Supporting Actor

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    Almost all routers and switches allow you you change the MAC address. The feature is call MAC Address clone or impersonation. Get the MAC address from the NIC inside your system and then plug it into your router or switch. Now it looks just like the original NIC to the outside world.
     
  10. Allan

    Allan Stunt Coordinator

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    Again, thanks everyone for your help. Both computers (desktop and laptop) run Windows XP. Andrew_W - are you saying that SethH can solve his problem? I am not sure what MAC and NIC mean but my problem sounds like SethH's in that the school do not allow us to connect multiple computers to a single ethernet connection.

    Keith - I did what you said and determined that my desktop (currently connected to the ethernet connection) is DHCP (the box you referred to says "Address Type Assigned by DHCP."

    So, I understand I need to buy a wireless router... Then what? How do I get both the laptop and the desktop to work with it considering the problem I mentioned above (with the school)???

    thanks
    Allan
     
  11. Bill Slack

    Bill Slack Supporting Actor

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    SethH:

    You can hook it up and set it to spoof your desktops MAC address. You'll be breaking the rules I suppose, but I doubt they'll notice.
     
  12. Andrew W

    Andrew W Supporting Actor

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    go to the command prompt and run ipconfig /all:

    C:>ipconfig /all

    Windows IP Configuration

    blah, blah, blah...

    Ethernet adapter Intel Pro 1000:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Intel(R) PRO/1000 MTW Network Connection
    Physical Address. . . . . . . . . : 00-08-74-4F-0C-89

    That's the part you're interested in. The Physical address, also known as a MAC address. That's the part that's unique a identifier of the network card to which they assign the IP address.

    The way the set up some DHCP servers, they will only assign IP addresses to known network cards. Now write that down.

    Dig into your router / switch docs and find the part about MAC impersonation or cloning. Put this number into the user assigned MAC address field and enable user assigned MAC address. (This will vary by brand, but almost all of them have it.) Save the settings and then power cycle everthing. When it comes back up, the DHCP server will give your IP address to the router. On the other side of the router it looks like you are a single computer with the assigned MAC address.

    This should work in 99.9% of the setups out there.

    Allan, you should get a combo switch/Wireless Access Point. Typically they can wire 4 computers with ethernet cables and service another 200 over the wireless.
     
  13. Keith Mickunas

    Keith Mickunas Cinematographer

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    Allan, there are a few things you can do to see how this will work out. First, set up your laptop to get it's IP via TCP/IP for it's ethernet port, then plug it in to your school's ethernet port. If that works, then you aren't going to have any trouble at all. You just get the router and follow the instructions in there and like I mentioned above. You'll set the router to receive it's IP via DHCP, and it will also provide DHCP addresses to your two PCs that are not associated with the school. As far as the school will know, you have one PC hooked up to the school, but really they're seeing the router which is dishing out the connection to both your computers.

    However if when the laptop is configured for DHCP and it doesn't work when you plug it into the shool's connection, then it gets tricky. There are two ways I know of to lock a DHCP connection to a specific computer. Sometimes the ISP will want the PC connected to the internet to have a specific host name. This is the way AT&T did it with my first cable modem. This isn't so hard to fool, you'll just give the router that host name. You can usually find the computer's name by right clicking on My Computer and looking at the properties or by running "ipconfig /all" and looking at Host Name. If you see something weird in there, that has no connection to you or your computer's manufacturer, it's possible the school set that to identify it to the network. You'll just have to rename your PC to whatever you want and set the router's Host Name to that field.

    Second, they could lock it by MAC address as Seth, Andrew and Bill discussed. The router's will work with this. To find the MAC address look at "ipconfig /all" and look for Physical Address. It's a 16 character identifier.

    Just so you know what all this means: IP address is a unique number all computers need to be seen on the internet. It's a four byte number, and is represented by four one to three digit numbers and falls in the range 0.0.0.0 to 255.255.255.255. These numbers are assigned in groups by the companies that give out the access.

    Now because those are limited, there is a way to spoof the system, called Network Address Translation, or NAT for short, it's sometime called IP Masquerading also. NAT is done when you have one device connected to the internet, and several other devices are connected to it with private IPs. A router can do this, or a PC can be configured to do it. In this way multiple PCs effectively share one IP address. It's quite commonly done. Companies often do it, and people with small networks do it. I have eight devices connected to a wireless router using NAT because my ISP only provides one IP number to me.

    MAC addresses are unique to actual hardware devices. These are 8 bytes long, and are usually displayed using hexadecimal numbers. Hex is a way of represent 16 digits with one character, you count 0 to 9, then A to F. A is 10, F is 15. 10 in hex is actually 16. One byte, which can be a value of 0 through 255, is represented in hex by 00 through FF. MAC addresses consist of 8 of these. Ranges of MAC values are assigned to the hardware manufacturers, and the possibilities are so big they'll pretty much always be unique. Every network card, router, etc., that has a network port on it has a unique MAC address.

    I know this seems like a lot of stuff you got to know to get your computers on the internet, but trust me, it's not so bad. The wireless access point/cable dsl routers are ideal for this situation. The directions should be pretty well laid out if you go with one of the major brands. They may even walk you through the process of determining if you need to clone the MAC address. Also, if you can find any computer majors there, ask them. They'll likely have already figured this out a long time ago.
     
  14. SethH

    SethH Cinematographer

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    Thanks. I was unaware that newer routers offered this. My router, a D-Link DI-701 does not offer that feature. I've found a cheap Belkin on eBay that offers that feature and I think I'm going to go ahead and pull the trigger on it.

    Thanks again.
     
  15. Allan

    Allan Stunt Coordinator

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    Thanks again to everyone for trying to help me out! Anyway, I tried what Keith suggested and first configured my laptop to DHCP and then plugged the ethernet connection into my laptop. It didn't work...

    So, is the solution as follows: first, buy a router that will spook my desktop's MAC address. Then, enter my desktop's MAC address (which I have located thanks to Keith's instructions) into the router. Then, connect the desktop and the laptop to the router. Will this work???

    One question though -- is it problematic that both the desktop and the router will have the same MAC address?

    Also, I just need to make sure that the router I get has "MAC impersonation" or "cloning", correct?

    Is there anything else I should be aware of?

    THANKS AGAIN!!!

    Allan
     
  16. Keith Mickunas

    Keith Mickunas Cinematographer

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    It's usually called cloning or spoofing. I think most have it. My D-link 614+ does. In fact my can read the MAC from the PC and copy it just making it that much easier for you.

    I don't believe having a PC and with the same MAC will be a problem. However if it is, the simple solution would be to buy a new card for your PC. A PCI ethernet card can easily be bought for $10 to $15. Or for a bit more you can get a USB to ethernet adapter. There is no problem with having multiple ethernet adapters, so if your PC's is built in you just leave it alone. If it's an add-in card, just swap it.
     
  17. SethH

    SethH Cinematographer

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    Just so you know I found several routers on eBay for about $20 that do MAC cloning. I just bought a belkin that includes a 4-port switch. Got it new in box for $26 including shipping.
     
  18. Allan

    Allan Stunt Coordinator

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    Ok. I found a router that does MAC cloning (it is the Linksys BEFW11S4. Anyway, before I purchase it (or another router), I thought it would be best to review the manual. I found it on line and, based on everything I learned above, it actually makes sense to me. However, one quick problem/question before I pull the trigger on this thing:

    In configuring the router, the manual says that your ISP may require a "Host Name" and a "Domain Name." How do I figure out if my ISP requires such names and if it does, what those names are???? In other words, is there some way to look at my desktop's settings (which is currently connected to the ISP and determine whether I need those names and if so what they are)???

    THANKS AGAIN!
    Allan
     
  19. Keith Mickunas

    Keith Mickunas Cinematographer

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    Take a look at ipconfig /all and it will display your host name. That is the same as your computer's name in windows. Just post it on here, and tell me what kind of computer you have and the OS as well as your school's name and I'll help you determine if it's necessary or not.

    The domain name isn't really an issue I don't think. My router doesn't even take it. You might find it under the TCP/IP properties that you looked at to determine if you had DHCP. Click on the advanced button, that'll bring up a dialog called Advanced TCP/IP Settings. Look through all the tags and see if you see anything that says "schoolname.edu" or something similar. If you can't find anything, I wouldn't worry about it.
     
  20. Mark Dubbelboer

    Mark Dubbelboer Screenwriter

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    that's a good router allan. I have the same one and it's really easy to get into the menu and do any changes from there that you'll need to do.
     

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