say when @Francesc099

Ok, I have translated it. You were very clear, thanks. You can continue

so now we are in the situation, that one guy flicks his switch and the siren rings in all the 3 other guys rooms.

Damn his explanations are good.

that's what we'd call a broadcast

but usually, we only want to send a message to one guy at a time

a so called unicast

so what we would do is, attach an "address" in front of our message we send on the bus. now everyone that doesn't hear his identifier first, might just not listen to the message

a so called unicast

You are perfect as teacher

looking at modern computers, we would add a "filter" between our databus and our memory. and we would electrically build that filter in a way, that only data gets passed through it, that has our explicit address in it

you need to understand, that right now, we are talking of a physical address, which is electrically embedded into our filter

thats the idea of a MAC address,... somewhat

(even though modern mac filters work somewhat differntly, nevermind, we are talking about primitive computers here)

okay, so now, we have a databus, and we can send messages to this bus, by electrically modifing it and we can filter out messages, that are meant for us by our mac address

what a great technology!

this second step,... with the mac address.

we'd call it level 2 networking, or: data link layer

What a great explanation!

alright, next step

lets assume, that beyond our network-card. (the thing that filters the messages) there are a couple of computers running

Alright

or lets say, there are different systems active.

now we would have to decide, with which of those systems we'd like to communicate

so we would just give away addresses for all of the subsystems inside one computer

on software-level

that is where the IP address comes into play.

you don't really need to know where this address comes from, lets just say, a network admin gave it to you to specifically identify a subsystem on your computer

et voila: there you have level 3

the so called network-layer

and there is a great thing happing here!! watch out: not only, can I send you a message and refer to a specific subsystem on your machine, but also 2 subsystems on the same machine could use these addresses to communicate with oneanother!

okay, but what is this IP address... first of all, it is basically a block of memory, that the OS writes everything to, it receives

not more not less.

clear so far @Francesc099

Yeah, you are great

I am understanding everything

great!

we could say: that the IP address is like a small channel into your operating system. into your user-space

a piece of memory, that can be written from the outside and read from within the OS

but we still have a problem here. usually, there is not only one process running on an os, using the network. there are 2, 5 or 100 processes all using network

so if a new packet arrives, which process should be notified by the operating system?

believe me @Francesc099 there were times that wasn't that clear and it was a great mess

so the idea people had was.... IF a process, wants to do networking stuff, this process should as the operating system to get its own inbox.

like a parking-slot for a small ship of data

and that way, technology went and we started to call such addresses inside of an operating system Ports

so the idea people had was.... IF a process, wants to do networking stuff, this process should as the operating system to get its own inbox.

Protocol?

and that way, technology went and we started to call such addresses inside of an operating system Ports

Oh ok

Protocol?

actually all of the discussed topics ARE protocols

a protocol is just a piece of paper, in which two sides of a communication promise oneanother to only use the specified technologies to communicate ;)

a protocol is just a piece of paper, in which two sides of a communication promise oneanother to only use the specified technologies to communicate ;)

Ahahah thanks

on level 1, a protocol could be wifi or cat-cable

on level 2 you could refer to MAC as some kind of protocol (although there are a lot of other things in between like CSMA and all that crazy stuff we won't get into tonight)

on level 3 the protocol we talk is IP

and on level 4, the level we are now on, 2 of the most used protocols are UDP and TCP

and on level 4, the level we are now on, 2 of the most used protocols are UDP and TCP

Yeah, I've heard of them

we also call level 4 the transport-layer... please don't ask me who picked that name.

we also call level 4 the transport-layer... please don't ask me who picked that name.

Ahahaha ok

okay. but to conclude, i can send data, via two cabels (eth) to the correct network-card (MAC) which gets forwarded to the correct subsystem (IP) and to a specific process on that IP (Port)

isnt that great?

every time i think about this, i can't believe my own thoughts. its so complex, yet so easy and obvious

we are now starting to touch the crazy protocols.... the level 5. which is the level we would like to operate on

over the last few years, people have started to write so called RFCs.

we are now starting to touch the crazy protocols.... the level 5. which is the level we would like to operate on

Ok, I am ready

in some of them, people claim to set a fixed port, not for a specific program, but for a specific purpose

so, there are multiple vendors of genuine website-servers

Why do you even giving this shit...

BUT,... if your browser wants to get a text file from a specific IP address, that can be represented as a website, it knows that this webserver will "listen" for incoming calls on Port 80

you get the idea @Francesc099 ?

programs/processes might use ports to communicate

if we want to communicate a special thing, we use a special port

BUT,... if your browser wants to get a text file from a specific IP address, that can be represented as a website, it knows that this webserver will "listen" for incoming calls on Port 80

hopefully 443 :)

hopefully 443 :)

:D yeah

okay.... excercise right now, while I go and get me something to drink, @Francesc099, please find out what we communicate on port 443

😂

okay.... excercise right now, while I go and get me something to drink, @Francesc099, please find out what we communicate on port 443

Ahahahah ok😂

i am back, how about you?

klimi is back too, now with double the amount of warnings he gives

i am back, how about you?

Thanks so much for the explanation

I like your office

I like your office

hehe, thanks, but what is the answer?