On Feb 5, 2004, at 4:01 PM, Steve DeLaney wrote:
My home network looks like this:
cable
modem
^
|
v
xbox <-> 802.11b game adaptor <-> Linksys 802.11b WAP/nat router <->
wired 10/100 network
^
^
|
|
v
v
voice e
thereal
headset
on
and w
indows
game
controls
What does the "wired 10/100 network" consist of?
I.e., is there some Ethernet box of some sort into which the Windows
machine running Ethereal, and the cable modem, are both plugged?
If so, then:
the "tap point" for ethereal is my laptop on the wired 10/100
network. Since every packet must pass through the cable modem, I
believe this configuration should let me capture packets for xbox.
...your belief would be correct only if all packets going to the cable
modem had to pass through that Ethernet box in a fashion that would
allow the machine running Ethereal to capture them.
However, if the Ethernet box is a switch (which includes "switching
hubs" - apparently many cheap "hubs" these days are actually "switching
hubs", which are switches, not passive hubs - and many "broadband
routers", which have switches built into them), that's not the case - a
switch won't pass all traffic through it to all ports.
And if the box is a 10/100 dual-speed hub, those behave as if they had
a 10 Mb hub and a 100Mb hub connected together by a switch, meaning
that 10Mb traffic won't be seen on 100Mb ports unless
the traffic is being unicast to a machine on a 100Mb port;
the traffic is broadcast or multicast;
and vice versa.