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ETHERNET AND SEX

Cloning your MAC address. 

Basically, every ethernet interface [commonly called a "NIC" - Network Interface card] has a "MAC" address.  In the protocol world, that is how different ethernet network interfaces [most newer PCS will have one of these] are distinguished on a network. This is layer 2 stuff, if you care. Internet IP addresses are layer 3!  TCP ports are layer 4! Think of layer 3 addresses as unique  in the world.  Layer 2 addresses are local to your town [now don't go getting technical on me..... I know a MAC is unique, I am just trying to show it is used locally!].

Cable modem service is typically registered via your MAC address.  If you have a simple cable modem, the MAC address most likely corresponds to that of the cable modem.  If you are unlucky, it corresponds to that of the NIC [the ethernet interface card] in your PC.  Unlucky, because if you ever change your PC or your NIC card, you will have to call up your friendly cable modem help number and tell them the new MAC address.  You can find this via a simple "winipcfg" in Win9X, where it is listed as the "adaptor address."  In WinXP/NT4/2K it is the "physical address" listed when you do an "ipconfig /all."  If you want to add a NAT/router between your cable modem and your PC, the NAT/router will now take the IP address from the network, and you must register the MAC address of the NAT/router.  However, many of the NAT/routers will allow you to change the MAC address of the WAN interface, so that you can make it the same as the NIC on your PC was.  This means you don't have to call and go thru any re-registration.  The duplicate MAC address doesn't have any effect because it is on another "network [the other side of the NAT/router]."

The same technique applies to ADSL services which provide you with a bridged service instead of a ppp service.  Most ADSL service is provided via a ppp interface, even if you are using an ethernet modem or router connected to your ethernet NIC in your PC.  So ppp service does NOT require MAC address registration - it relies on your username and password, just like dialup service, which is why the ISPs like it - it fits into their existing management of you.

This page contains some troubleshooting techniques you can employ for your networking connections.

TCP/IP STUFF

WIRELESS STUFF

PC STUFF

ADSL/CABLE MODEM STUFF

 

Copyright John D Loop Saturday January 22, 2005