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  • access to Internet from a host

    What goes in the MAC field if a packet destined for the internet, the gateway, or what?
    There once was a Windows box with no firewall. Keyword is, there once was.

  • #2
    The sending computer inserts the MAC address of its interface when building the packet. Each router on the Internet overwrites this field according to their own addresses.

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    • #3
      Thanks a lot. But, where do you send a packet? I am writing an OS, and I need to know this so that I can get some basic network drivers working when I am ready. I read a few books of TCP/IP and Ethernet, but neither specified what is in the to/from fields of an internet-bound packet, how to autodiscover a gateway address. A google search or ten only turned up garbage results such as "The purpose of routing is to flip out and kill people." Any help at all will be much appreciated. And, is this the from or destination MAC address field that your own MAC is in? Sorry if I seem like an idiot, bat I get confused easily and have a bad habit of making run-on sentences.
      There once was a Windows box with no firewall. Keyword is, there once was.

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      • #4
        I was speaking of the from address.

        The destination MAC field should be the gateway. The closest thing to autodiscovering the gateway in IPv4 is DHCP (which gives you, among other things, the IP address of the gateway). You must make an ARP request to the network for that IP address, and, if you receive a response, use the resulting MAC as the destination.

        W. Richard Stevens should explain this in the popular TCP/IP Illustrated, Volume 1: The Protocols.

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        • #5
          Thanks a lot! Now I am off to run a google search trying to find stuff on DHCP!
          There once was a Windows box with no firewall. Keyword is, there once was.

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          • #6
            Originally posted by Hextic
            A google search or ten only turned up garbage results such as "The purpose of routing is to flip out and kill people."
            That's one of three important facts, the other two are:

            1. Routers are computers.
            2. Routers route ALL the time.

            I heard that there was this hacker who was DoSing at an open WiFi AP. And when some router dropped a packet the hacker killed the whole town.
            a pc-0x90 by any other name is a nummish..
            Bigger 1:23

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            • #7
              Originally posted by pc-0x90
              That's one of three important facts, the other two are:

              1. Routers are computers.
              2. Routers route ALL the time.

              I heard that there was this hacker who was DoSing at an open WiFi AP. And when some router dropped a packet the hacker killed the whole town.
              You forgot about the dog with a boner watching it, then exploded, but aside from that, 100% truth.
              It was so sweet I crapped my pants!
              Aut disce aut discede

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              • #8
                Originally posted by AlxRogan
                You forgot about the dog with a boner watching it, then exploded, but aside from that, 100% truth.
                It was so sweet I crapped my pants!
                When/where was this?
                There once was a Windows box with no firewall. Keyword is, there once was.

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                • #9
                  Originally posted by Hextic
                  When/where was this?

                  Ahhhhh hahahaha.


                  It was a very 31337 hax0r named Ashida Kim .

                  You can read more about him here .


                  LosT

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