RE: CSMA/CD

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To: Security-basics@securityfocus.com
Date: Thu, 21 Aug 2003 23:09:42 -0500

>> Does this mean that IF you were to write this program, you'd actually

>> need to rewrite a part of the tcp/ip protocol stack?

> As someone else has pointed out, this is probably normally done as
part of the Ethernet >port hardware. At best, it might be in driver
code. Since Ethernet can be used to carry >AppleTalk, DECNet, IPX, etc,
it's not in the TCP/IP part of the stack.

This is done at the hardware level. Think of the OSI model. Collisions
take place at the physical layer. CSMA/CD is an access methodology,
which is located at the physical layer. Appletalk, DECNet, IPX,
TCP/IP, etc are suites of protocols existing at layer 3 and above. You
can technically run these protocols on a CSMA/CA network (i.e. Token
Ring), because the protocol stacks don't really care what is happening
at the physical layer. So, like David said, the closest you could come
to this type of disruption would be a DoS attack (which is generally a
layer 7 occurance).

-Greg

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• Previous message: John Shao: "block un-authorized computer in VLAN"
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