Registered: Mar 2000
Location: Valencia, Ca
quote:MANY? Virtually everyone is using DOCSIS now, which creates an encrypted link to your head-end. Not only can you not communicate directly with your neighbors, if you did, all you'd get is an encrypted stream. Someone would need some severely expensive and fancy hardware to be able to sniff their neighbor's traffic.
On a DSL connection you can't go beyound your home with anything that isn't routed. On many cable model connections you can view use non routed protocols to communicate with other people on your local segment. This is a huge security problem. Arp, netbui, IPX, etc. to your neighbors computers.....
Netbeui? IPX? Those won't even go out over a cablemodem. ARP is not a "networking protocol" in the same sense as IPX, rather it's how your PC resolves a MAC address from an IP address. Normally, if you have a LAN with a bunch of PCs on it, you'd put them all in the same subnet. In that case, you'd want them to all talk directly to one another, and not go through a router. So, what happens is, if you send data from one IP to another on the same subnet, your PC will generate an ARP request to find out what the MAC address of the desitnation network card. On a cablemodem network, this is a problem because "other members" of the same subnet are in a different physical location. You really need to ROUTE rather than broadcast. So what happens is your cable headend takes the ARP request and rebroadcasts it to all your neighbors so their PCs can respond if they're online. This is called proxy-arping.
ARP does not contain sensitive information. It's simply "WHO HAS x.x.x.x TELL x.x.x.x" The only reason you've been hearing about ARP lately is that the current rash of viruses like to try and spread to other members of the same subnet, generating a ton of ARP traffic on a cablemodem network, causing modem lights to blink.
Disclaimer: There may be errors in my interpretation of the documentation I've read. IANANA (I am not a network admin)
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