AAA Configuration on Cisco Switch

In this lesson we will take a look how to configure a Cisco Catalyst Switch to use AAA and 802.1X for port based authentication. If you have no idea what AAA (Authentication, Authorization and Accounting) or 802.1X are about then you should look at my AAA and 802.1X Introduction first. Having said that, let’s look at the configuration. I will use the following topology:

aaa cisco switch elektron radius

I will show you an example of 802.1X with a RADIUS server. I am going to use Elektron RADIUS server as the authentication server because it’s easy to install and has a nice GUI.

RADIUS Server Configuration

Elektron Radius Wizard

Using a RADIUS server like Elektron will save you the time of hassling with installing Windows Server, configuring Active Directory and checking many checkboxes or messing around with Freeradius on Linux. When you configure a RADIUS server you will need to create a shared password:

Elektron Radius Server

I’m going to use “radiuspass” to keep things simple. Hit Next and you will see this:

Elektron Digital Certificate

There are different methods for authentication, for example:

  • Only username and password.
  • Username, password and a digital certificate on the server.
  • Username, password, digital certificate on the server AND on the clients.

In a production network you might already have a certificate authority within your network. I don’t care about certificates for this demonstration but we’ll generate them anyway in case you want to play with them sometime in the future. The next steps will let you configure a name for your RADIUS server and if you want the digital certificate, you will get some questions about it. Once you are done you will be in the main screen of Elektron:

Elektron Main Screen

By default everything should work out of the box so we don’t have to touch anything. Let’s start and add a user account:

Elektron Accounts

I want to create a new user account. Click on authentication, Elektron accounts and then on the big green plus symbol in the menu.

Elektron Add User Account

My new user account will be for Alice. My password will be “safe” and I don’t need her to be member of any groups. Click on OK.

Elektron Authentication Domains

By default Elektron will check Windows usernames instead of its own database. We need to configure it so the local database is used. Click on “Authentication Domains” and then on “Default Authentication Domain”.

Elektron Accounts Authentication

Change it to “Elektron Accounts” and click on OK. That’s all you have to do on the Elektron RADIUS server, we’ll look at the switch now!

Switch Configuration

First I need to make sure SW1 and the Elektron RADIUS server can reach each other. We’ll use the management interface (VLAN 1) and configure an IP address on it:

SW1(config)#interface vlan 1
SW1(config-if)#ip address

Now we should enable AAA:

SW1(config)#aaa new-model

This is an important command. Use aaa new-model to unlock all the different AAA commands that we need. Let’s configure the RADIUS server:

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Forum Replies

  1. What’s the name of the follow-up lesson? “In another lesson I will give you a configuration example how to implement this on a Cisco Catalyst Switch.”

    Or does it not yet exist?

  2. Hi Francesco,

    We use RADIUS and TACACS+ for both user authentication and management. For example, with wireless networks we use RADIUS for user authentication (WPA2-enterprise). This allows us to use client and server certificates and it’s a far more secure solution than using pre-shared keys only.

    For network management, it’s useful since you can centralize all your authentication instead of creating usernames/passwords on each and every router, switch, firewall, etc on your network.

    It’s used on local networks, the only time you might use it on the Internet i

    ... Continue reading in our forum

  3. oh, thank you so much, i looked it out :slight_smile:

  4. Hello Markos

    Using port security we can do several things. We can restrict the use of a switch port to only one specific preconfigured MAC address or we can specify that only a single MAC address should be seen to be using this port. We can even use IP source guard to determine which will be the allowed source IP address that can use the interface, even on an L2 switch.

    The first case will allow us to lock the port down such that only a specific computer having a specific MAC address can connect to that port. If this were implemented, then port security woul

    ... Continue reading in our forum

  5. Hello Justin

    If I understood your argument correctly, you mean connect something like an access point or a SOHO router to the port-security enabled switchport and have that device perform NAT, where all hosts connected to that device will communicate on the network via the 802.1x enabled port using a single MAC and IP address, thus defeating port security, correct?

    Yes, this would “defeat” 802.1x if you had configured it to allow any single MAC address. However, you can configure it to allow only a particular MAC address, that of the only allowed workstation o

    ... Continue reading in our forum

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