In the CCNA course, we've been discussing the use of local usernames and passwords, in other words,
the username and password information is stored on each router or switch individually.
So as an example, when I log on to this router, router 1 there's no authentication.
But what we could do is create a username on the router and then go into the line console and specify
login and either a line login or specify a local login.
So now when we log on to the router, we are prompted to enter the username and password that works
well when you have a small environment, but as you scale, it becomes a lot of work.
So as an example, when I connect to router 2 there's no username and password.
So what I need to do now is create a separate username and password on Router 2
and then
I need to remember to go into the line console
and specify a log in local, and I mustn't forget to do that on the VTY lines as well.
So logging back in,
I'm now prompted for my username and password on Router 2
but once again, when I connect to Router 3 there's no username and password and I have to specify
that again.
Now, that's not the only problem that we have to configure passwords locally on every device.
So you've got to remember to do all that configuration
but what you've also got to remember to do is to change your passwords on a regular basis.
To implement good security practices, you should be changing your password on a regular basis, that
means that we have to go to every device in the network and change the password on each device individually.
In this example of only got five devices.
But if you've got hundred or a thousand network devices, that's a lot of configuration that increases because
you don't want your users sharing the same username and password.
So if you've got another user in your environment
you should set up that user account on every router, so as an example on Router 1, I can log in as
Mary
but I can't do that on Router 2.
Because I haven't configured a username, Mary, on Router 2, so the management of usernames and passwords
becomes very difficult when you have a local usernames and passwords configured on every device.
So it makes sense to centralize your usernames and passwords on a central server.
So in this example, we've got a user called admin, but we could add Mary or David to this database
and then point every network device to the central ACS server, which means that we don't have to configure
a local username and password on every device for every user that needs to access that device.
The server can also be leveraged once again for 802.1x authentication, where you centralize
the username and password authentication of users accessing the network through a triple A server or
authentication, authorization,
and accounting server.