From Slashdot: Comcast goes after NAT users-MAC Addr

[David Carter]

----- Original Message -----
From: "Jeremy Fowler, CNA" <jfowler at westrope.com>
To: "Kclug" <kclug at kclug.org>
Cc: <phidias at netgate.net>
Sent: Friday, January 25, 2002 12:15 PM
Subject: RE: From Slashdot: Comcast goes after NAT users

<snip
>
>     Host A    ^                      ^    Host B
> [Application] | <------------------> | [Application] SMTP, HTML, DNS
> [ Transport ] | <------------------> | [ Transport ] TCP, UDP
> [  Network  ] | <------------------> | [  Network  ] IP
> [ Data Link ] | <------------------> | [ Data Link ] Ethernet
>               |______________________|
>                 Actual Flow of Data
> >
> Example TCPIP Packet:
>
> Application Layer starts with the data:
> [        DATA        ]
>
> Transport Layer encapsulates the data and adds it's header:
> [ TCP HEADER [        DATA        ]]
>
> Network Layer encapsulates the Transport Layer packet and adds it's own
header:
> [IP Header (IP Address) [ TCP HEADER [        DATA        ]]]
>
> Finally the Data Link Layer encapsulates the other layers and adds the
last
> header:
> [ Ethernet Header (MAC Address) [IP Header (IP Address) [ TCP HEADER [
> DATA        ]]]]
>
>
> So when the packet is received on the other end, the MAC address IS the
address
> of the originating device. Not the last router that encountered the
packet.
>
> IP Masquerading changes the IP Header information ONLY, not the MAC
address.

Jeremy,

Re, ". . . the MAC address IS the address of the originating device. . . .":

1)  What does the acronym MAC stand for? (just curious, not important to me)

2) What is the originating device?  The Syslink 4 port router (firewall)
that my 2 or 3 computers are tied into, which then goes out the DSL modem?

David Carter