So our next section is on protocols in port numbers, and this is a big portion of the exam.
You just spent some time going through the OSI model and the TCP I P model.
We've talked about the fact that TCP IP is really a protocol suite with lots of different protocols that make up the sweet.
Each one of those protocols has a port number assigned to them.
A port number is a software identify their thought. When the traffic gets to your system, your system knows which application or service is needed in order to process the traffic.
So with your port numbers, there's sort of an endpoint for communication.
They're not a physical port that you plug something into but their conceptual entryway into the system.
So when one system is going to connect to another system via the network, they have a conceptual port number.
Now, with the report numbers, there are what are referred to as well known ports, which is mostly what we're going to work with.
The idea is that all of these protocols that we're going to talk about in class these application layer protocols and application layer services all have ports that are assigned to them so that by default, Web traffic is port 80 DNS. Traffic is port 53 so on.
With these well known port numbers, you have to remember, from 0 to 1023 of the port numbers,
I just wanted to see who is listening there. You don't have to memorize 1023 port numbers,
but there are about 20 that you just need to know really well.
There will be a lot of poor questions on the exam, and hopefully some of you guys will stick around for the security plus exam as well.
You have to know your port numbers on that exam, too, so you might as well memorize with a smile, because these will come up multiple times
for your registered port numbers. Vendors will register certain sort of proprietary services or software with Diana, which is the organization that manages port numbers.
These are the ones that are reserved because they're used specifically by vendors.
There are dynamic ports from 49,152 all the way up to 65,535
and these are referred to as F. Romero ports.
These are temporary reports that aren't assigned to anything particular, but that can be used in order to indicate some sort of connection.
It's often used as a source port number
When Computer A connects to computer, be the destination I P Address is going to be computer bees, i p address and whatever service, for example, Web server Computer B Port 80.
What's also on the data pocket is the source address and a source port.
A source part is an arbitrary number, usually over 49,152.
Ultimately, that's a way of identifying when traffic comes back into the network.
It's often used with network address translation.
So when we talk about ports to memorize, I want you to focus on the well known ports.
I'll give you a list to follow in this section
for registered ports. Know what the ranges and that there for the vendors and proprietary things
for dynamic ports again wouldn't worry too much about specifics. For your own knowledge, know that source ports are pulled from that range