Subj : Re: Burning pixels
To   : tenser
From : Ed Vance
Date : Mon Sep 16 2024 12:11 pm


> On 14 Sep 2024 at 10:33a, Ed Vance pondered and said...

> 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)


WHEW!
Thanks, I knew bits of those things but You wrote things in details that I
never got around to learning.
Thanks Again.
Ed
--- SBBSecho 3.20-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)

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