Subj : Re: Burning pixels
To   : Ed Vance
From : tenser
Date : Tue Sep 17 2024 01:57 am

On 14 Sep 2024 at 10:33a, Ed Vance pondered and said...
 
 EV> What's bothering me about Wi-Fi is that I never read anything about how
 EV> to get Firefox and Thunderbird to send their Output to USB instead of to
 EV> a Router to get to the Internet .
 EV> 
 EV> Only one of my computers could be used at a time unless there is a way
 EV> that a USB Hub could have both of my pc's connect to the USB Wi-Fi
 EV> dongle.

Oh dear.  I'm afraid that this is just not how things work.

The short of it is that the Internet is conceptually modeled
as layers; applications like Firefox and Thunderbird "speak"
application-level protocols (like HTTP) over transport- and
session-layer protocols (like TCP and SSL/TLS, respectively).
Transport layer protocols like TCP are _usually_ implemented
in the operating system, though there's no physical law of
the universe that requires that.  Anyway, TCP then layers on
top of IP, which in turn layers on top of a link-layer
protocol like Ethernet, which layers on top of a physical
layer protocol like 1000Base-T over twisted pair, or 802.11
"WiFi" over an RF link.  And that's not counting how any
of the devices that implement physical and link-layer protocols
actually connect to the computer; common modern standards
include PCIe (for high speed devices) and USB (for fast, but
perhaps not _as_ fast, devices).

All of this is to say that the layers between a program like
Firefox and the decision between which link-layer interface
to communicate the traffic it sends and receives on, are designed
for mutual isolation: Firefox doesn't know, or care, what
interface the OS choses to data it sends on; it just seems a
virtual stream abstraction.  Similarly, the OS doesn't care
which stream traffic transiting a USB Ethernet interface, WiFi,
Bluetooth, or whatever is associated with; that's all handled
at a higher layer (first IP and then TCP or UDP or whatever).

If you have multiple computers connected to an internal IP
network, they will all have to have unique IP addresses and
routes in order to communicate with the Internet at large.
Although it wasn't initially designed this way, if you are
using IPv4 (which you almost certainly are) for most consumer
situations this means you need some sort of router at the edge
of your home network that will do Network Address Translation,
allowing multiple _internal_ devices to share a single _external_
address (more properly, this is usually done with Port
Network Address Translation, or PNAT).  Fortunately, most
commercially available consumer routers have this built in and
do it automatically.

Hope that helps a little bit.

--- Mystic BBS v1.12 A48 (Linux/64)
 * Origin: Agency BBS | Dunedin, New Zealand | agency.bbs.nz (21:1/101)