So although we stored the passwords with a strong encryption algorithm, it's still not safe to let
just anyone access the password hashes because they're still open to the offline password cracking attacks.
So it's possible to identify access control list for the communications services, such as an MP, as
I say in Telnet, with these access lists, we can decide who can and cannot connect to the services,
then close the services for everybody else.
So there are two types of access lists, standard and extended.
Let's have a look.
We can see how we can manage the access to the router.
So once again, we are back in the network, had we created by using Ginés three, all the devices are
still active and running.
That's always a good time.
Over the routers console.
And enter the config terminal mode.
Access list is the key word to create and configure access control list, so put a question mark to
see the options.
The number here decides the type of the access list will make an example of standard access.
So just put a number between one and ninety nine to.
A standard access control list either denies or permits source IP addresses.
In addition, a source, IP addresses and extended access control list can also deny or permit based
on destination IP addresses, ports and those services as well.
Questionmark again, and these are the options we can either deny or permit a connection request.
So let's decide who to permit first questionmark to see the options.
OK.
We can put a pattern here, so the computer's matching the pattern are allowed.
If we use any here, that means we permit all computers except ones which are identified by the Dinni
and the access list.
Alternatively, we can permit directly to any specified computer.
So here, I'll use host as the option and let my colleague access to it.
So let me look at the IP address of Akali ten point three.
I want to deny all others so access list to deny any.
Now, the next thing we have to do is go to the line VTE y and apply this access list to the interface.
Good, so type line y zero 04 to enter line config.
In the line config will use access list command.
Number of access lists first and now a question mark to see the options and look at that, there are
two options in and out.
Now, since we're going to be telnet into the router, we're going to use in.
Exit or control, see the exit from the line config mode.
Now, I want you to see the running config, so type show run.
And here is the running config, so scrolling down show, showing the access list and make sure that
everything's right.
So here it is and yes, as you can see, we have our access list to to permit Colly and deny any other
host attempting to make a telnet connection.
Now, let's test whether the access list works as intended.
So back in my network, I have other pvm machines like Colly, one of them is a WASP Bayway, as you
know, and it's IP address is turned out for.
First, I want to check if the network is OK and a WASP sees the router, so ping one nine two one six
eight one zero one and sure enough, we have a reply's.
Now I want to create a telnet connection to the router to type telnet and the router IP hit enter.
Connection is refused.
Well, that's what's supposed to be right.
That means the Dinni part of the access list is working properly.
What about the permit part to go to college in terminal screen telnet into the router and as you can
see, we can telnet into the router, the request is not refused and we are allowed to telnet from Colly.
So to double check, I'll run an end map query to check whether the telnet board of the router is open.
And yes, of course it is.