So let us begin with the first security filtering technique that is access control list.
It's rare to find a network around these days that aren't connected to the Internet.
The Internet is clearly a public Internet tool that anyone can connect to.
But your companies or postal network is and should be definitely a private one.
The catch is that every time you connect to the Internet from a public network, they're instantly vulnerable
to security beacons.
Now, this is where something we call a firewall comes into play.
Firewalls are basically tools that you can implement to prevent any unauthorized access around on public
networks.
And gaining access to a network of the firewalls can either be standalone devices or combined with another
hardware device like servers or routers.
Now, access control list is the primary weapon of the firewalls which help us to, you know, discard
unused packets.
Now, access control list, that is ECL is typically the list.
It's not kind of a list, but it kind of a program that resides on the routers to determine which packets
are allowed to run through them based on the requesting devices, source or destination Internet protocol
address.
That is the IP address.
Oh, and just so you know, issues have been around for many decades and have other uses apart from
firewalls as well.
Now there's an image on the screen which demonstrates an ACL enabled router.
OK, so what we can see here is I like my pen.
What we can see here is that users in the network e that they can access Network B, right.
Also, the package that can pass through the router are from this week from network to Network B.
Now, this means that an IP spoofing attack, when someone pretends to have a network address on the
inside of the firewall to gain the network, access can still happen if a user in the Network B pretends
to be located in the network.
So, for example, someone who is here but it is pretending to be here can also access the Internet
network because it is pretending that it's actually residing here now will see things like IP spoofing
more thoroughly in other sections of network threat and mitigation.
But for now, let's go back to Israel.
So which means B can access E if a secure authentication connection is so, B, can actually access
A.
Only if a secure authentication connection is used, for example.
But it can access the public network.
Now you can create a wide array of access control lists from the very simple to the highly complex,
depending on the exact what do you exactly want to have them to do for you?
One example is placing separate inbound and outbound access control on in order to ensure that the data
that is leading your network comes from a different source than the data that's coming into it.
Now, when configuring access control lists between the Internet and your private network to mitigate
security problems, it is a good idea to deny any address from your internal networks, then deny any
localhost addresses.
That is 127 DOT zero zero eight and deny any reserved private addresses.
Deny any addresses in the IP multicast address range that is to twenty four point zero point zero slash.
For now, none of these addresses should ever be allowed to your Internet.
Interestingly enough, because of the way in which in public IP addresses are issued with some research,
you can even create a filter that blocks a country, a state or even a local area based on the IP addresses.
If you want to know more about access control list, I guess I have already attached some resources
at the beginning of the section.
If I have not, please post a question and answer in the question.
Answer section.
I will immediately upload the book.
Well, that is it for this lecture.
I hope you have understand the function of access control list and why access control lists are important.