How to force a connection to go out of machine?

[James Knott]

Lennart Sorensen wrote:
> On Thu, May 16, 2013 at 07:18:07PM -0400, James Knott wrote:
>> >Well, with consumer level routers, the WiFi is generally bridged to
>> >the Ethernet, so it's not going to make any difference.  As for
>> >allowing foreign addresses, as I mentioned, that's basic firewall
>> >stuff and it would have to be a crappy firewall that allowed it.  In
>> >short, the router portion should not pass any traffic from an
>> >address that's not within it's configured subnet.  This is done to
>> >prevent spoofing.  On the other hand, industrial level routers can
>> >be configured to do that, with appropriate rules.
> Actually many routers I have seen have the wlan software bridged to the
> lan ports.
>
> In fact I am not sure I have ever seen one that wasn't done that way
> given the AP has to control the wifi port a lot, which would perhaps be
> harder if it was hardware bridged to the switch chip.

There's a whole lot that goes on between WiFi and the Ethernet switch 
part of those consumer routers.  Regardless, when all is said and done, 
Wifi traffic appears on that switch as though it came in via Ethernet.  
It's the same thing with stand alone access points, as I have here.  
It's plain Ethernet traffic, after the WiFi has been handled.  Other 
than apparent bandwidth, there's no way a user could tell if they were 
connected over WiFi or Ethernet, as the WiFi function is completely 
transparent in that regard.  As an experiment, ping a device connected 
via WiFi and then check your arp cache.  You will see the MAC address of 
that device, which means it's effectively on the switch or "bridged"¹ to 
the network.  If it passed through the router, you would not see any MAC 
for it, though the router's MAC would be listed.

1. A bridge and a switch are logically the same device in that they work 
at the Ethernet level and reduce/eliminate collision domains.

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