AAA: Authentication, Authorization, and Accounting

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Questions and Answers

Which of the following is the first step in the AAA process?

  • Auditing
  • Accounting
  • Authorization
  • Identification (correct)

What is the primary function of the 'Authentication' element within the AAA framework?

  • Recording a log of events related to system activity.
  • Verifying the identity of a user. (correct)
  • Tracking network usage for billing purposes.
  • Defining the allowed and denied resource access.

Which AAA element is responsible for granting or denying access to specific resources after a user has been authenticated?

  • Authorization (correct)
  • Auditing
  • Accounting
  • Authentication

Which of the following best defines the purpose of the 'Accounting' element in AAA?

<p>Tracking resource consumption for monitoring or billing. (B)</p> Signup and view all the answers

What is a key vulnerability when using Telnet without AAA?

<p>Vulnerability to brute-force attacks due to lack of security features. (D)</p> Signup and view all the answers

Which security protocol is used alongside a local database method to enhance authentication security compared to Telnet?

<p>SSH (D)</p> Signup and view all the answers

What command is used to enable AAA globally on a Cisco router?

<p>aaa new-model (B)</p> Signup and view all the answers

Which command configures the router to authenticate users against a local database?

<p>aaa authentication login default local (C)</p> Signup and view all the answers

What does the aaa local authentication attempts max-fail command control?

<p>The number of failed login attempts before locking an account. (A)</p> Signup and view all the answers

In server-based AAA, what are the two primary protocols used for communication with AAA security servers?

<p>RADIUS and TACACS+ (B)</p> Signup and view all the answers

What is a primary benefit of using server-based AAA over local AAA?

<p>Centralized management of user authentication and authorization. (B)</p> Signup and view all the answers

Which protocol, RADIUS or TACACS+, separates authentication and authorization?

<p>TACACS+ (A)</p> Signup and view all the answers

Which transport protocol does TACACS+ use?

<p>TCP (B)</p> Signup and view all the answers

What information is encrypted by TACACS+?

<p>The entire packet. (A)</p> Signup and view all the answers

What command is used to specify the IP address of the ACS server when configuring server-based AAA?

<p>address ipv4 (C)</p> Signup and view all the answers

After configuring AAA with TACACS+ or RADIUS, which command is essential to apply the authentication method to the login process?

<p>aaa authentication login default group tacacs+ local (D)</p> Signup and view all the answers

Besides TACACS+ what can be used communicate between clients and AAA security servers in Cisco Secure ACS?

<p>RADIUS (A)</p> Signup and view all the answers

Which of the following is true about RADIUS in the context of authentication and authorization?

<p>RADIUS does not separate authentication from authorization, which can limit flexibility compared to TACACS+. (C)</p> Signup and view all the answers

Consider a network where both RADIUS and TACACS+ servers are configured for AAA. The network administrator intends to prioritize TACACS+ for all authentication requests, but in case the TACACS+ server is unreachable, RADIUS should be used as a fallback. Which of the following configurations would achieve this?

<p><code>aaa authentication login default group tacacs+ group radius</code> (D)</p> Signup and view all the answers

A network engineer is troubleshooting a network where users are failing to authenticate. AAA is configured to use TACACS+ as the primary authentication method and local authentication as a backup. Local authentication is configured, but to the engineer's surprise, it is never used even when the TACACS+ server is completely unreachable and local users exist in the router's configuration. Why might the local authentication not be functioning as expected?

<p>The command <code>aaa authentication login default group tacacs+ enable</code> was used. (A)</p> Signup and view all the answers

AAA is concerned with identification, authentication, authorization, and auditing, but not accounting.

<p>False (B)</p> Signup and view all the answers

Identification in AAA involves validating a claimed identity before granting network access.

<p>False (B)</p> Signup and view all the answers

Authorization determines the level of access a validated user has to network resources.

<p>True (A)</p> Signup and view all the answers

Accounting in AAA is solely concerned with billing users based on their network usage.

<p>False (B)</p> Signup and view all the answers

Telnet, without AAA, is not susceptible to brute-force attacks due to its strong encryption.

<p>False (B)</p> Signup and view all the answers

When configuring local AAA, usernames and passwords must be added to a central external database.

<p>False (B)</p> Signup and view all the answers

The aaa new-model command is optional when enabling AAA on a Cisco router.

<p>False (B)</p> Signup and view all the answers

The enable keyword, in authentication methods, uses the enable password for authentication.

<p>True (A)</p> Signup and view all the answers

Local AAA is best suited for large networks with hundreds of devices.

<p>False (B)</p> Signup and view all the answers

AAA cannot be configured to lock out a user account after a specified number of failed login attempts.

<p>False (B)</p> Signup and view all the answers

Server-based AAA offers centralized management compared to local AAA.

<p>True (A)</p> Signup and view all the answers

TACACS+ and RADIUS are AAA protocols that are used to communicate between the clients and AAA security servers.

<p>True (A)</p> Signup and view all the answers

TACACS+ uses UDP for transport, while RADIUS uses TCP.

<p>False (B)</p> Signup and view all the answers

RADIUS encrypts the entire packet, while TACACS+ only encrypts the password.

<p>False (B)</p> Signup and view all the answers

In TACACS+, authorization and authentication are combined into a single process.

<p>False (B)</p> Signup and view all the answers

auth-port and acct-port are configurable parameters in RADIUS, specifying the authentication and accounting port numbers, respectively.

<p>True (A)</p> Signup and view all the answers

Microsoft's Network Policy Server (NPS) cannot be used as a RADIUS server for AAA.

<p>False (B)</p> Signup and view all the answers

AAA authorization is always required after successful authentication, since authentication does not imply levels of permissions.

<p>True (A)</p> Signup and view all the answers

In AAA accounting, a 'start' message indicates the end of a user's session.

<p>False (B)</p> Signup and view all the answers

To configure AAA accounting to use the RADIUS protocol on a Cisco router, the command aaa accounting exec default group radius must be used.

<p>True (A)</p> Signup and view all the answers

Flashcards

Authentication

Verifying a user's identity to grant network access.

Authorization

Determining what a user can access on the network.

Accounting

Tracking network usage for auditing and billing.

AAA

A security framework controlling network access.

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Authentication Purpose

Ensuring the device or user is legitimate.

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Authorization Purpose

Allows or disallows access to network resources.

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Accounting Purpose

Tracks network resource usage for auditing and billing.

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Local AAA Authentication

Router authenticates using a local database.

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Server-Based AAA

Router authenticates using a remote AAA server.

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TACACS+

A protocol for AAA, separating authentication and authorization.

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RADIUS

An AAA protocol combining authentication and authorization.

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Cisco Secure ACS

A system offering centralized AAA services.

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AAA with Active Directory

AAA integrated with Microsoft's directory service.

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Authentication

Ensures legitimate devices or end-users access the network.

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Authorization Definition

Allows or disallows access to specific areas or programs.

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AAA Accounting tracking

Provides comprehensive network usage data.

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Identification (AAA)

Claiming an identity when trying to enter a secured area or system.

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AAA Auditing

The component of AAA, which records a log of events and activities related to the system and subjects.

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AAA Accounting (Reviewing Logs)

Reviewing log files to check compliance and violations, holding subjects accountable for their actions.

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Telnet Vulnerability

When Telnet is directly exposed to the internet, it's susceptible to having passwords cracked by repeated login attempts.

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SSH Authentication

A more secure method which uses encryption and a local database, like SSH.

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AAA Max-Fail Attempts

A configuration mode command used to limit the number of failed login attempts before a user account is locked out.

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Show AAA Local User Lockout

The command used to display locked-out local users.

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Show AAA Sessions

The command used to view active AAA sessions.

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Server-Based AAA Authentication

User establishes a connection with the router, and the AAA server validates access based on the remote server's information.

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Server-Based AAA Configuration

It includes the AAA server's IP address and a shared secret key for secure communication.

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TACACS+ Encryption

It uses TCP for reliable communication and encrypts the entire packet for enhanced security.

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RADIUS Encryption

It typically uses UDP, encrypts only the password, and combines authentication and authorization.

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Study Notes

Chapter 3 Overview: Authentication, Authorization, and Accounting (AAA)

  • AAA is critical to network security.
  • The main elements consist of identification, authentication, authorization, auditing, and accounting.

AAA Elements

  • Identification involves claiming an identity to access a secured area or system.
  • Authentication is proving you are that identity.
  • Authorization defines the allows and denials of resource and object access for a specific identity.
  • Auditing involves recording a log of events and activities related to the system and subjects.
  • Accounting is reviewing log files to check for compliance and violations to hold subjects accountable.

Authentication without AAA

  • Telnet is vulnerable to brute-force attacks.

Authentication Modes

  • Local AAA authentication involves the router authenticating users against a local database.
  • Server-Based AAA utilizes a remote AAA server for authentication.

Authorization

  • Once a user is authenticated, the router requests authorization from the AAA server for requested services.
  • The AAA server then returns a pass or fail.

Accounting

  • Accounting tracks network connections, EXEC sessions, system commands, and resource usage.
  • The AAA accounting process generates a start and stop message to record when the process began and ended, respectively.

Local AAA Authentication

  • AAA can be configured via the CLI to validate users against a local database.
  • Troubleshooting validates users against a local database.

Authenticating Administrative Access

  • Add usernames and passwords to the local router database for users that need administrative access.
  • Enable AAA globally on the router and configure AAA parameters.
  • Confirm and troubleshoot the AAA configuration.

Authentication Methods

  • 'enable' uses the enable password. ‘local’ uses the local username database for authentication.
  • 'local-case' uses case-sensitive local username authentication, and 'none' indicates no authentication.
  • 'group radius' utilizes the list of all RADIUS servers.
  • 'group tacacs+' uses the list of all TACACS+ servers for authentication.
  • 'group group-name' uses a subset of RADIUS or TACACS+ defined by specific commands.

Server-Based AAA

  • Server-based AAA centralizes user management, which is beneficial for scalability and consistency.
  • TACACS+ and RADIUS are compared as server-based AAA authentication protocols.

Local vs Server-Based AAA

  • Local authentication involves the user establishing a connection and being authenticated against a local database.
  • Server-based authentication also involves establishing a connection, but it is passed to a Cisco Secure ACS for authentication

Introducing Cisco Secure Access Control System

  • TACACS+ or RADIUS protocols communicate between clients and AAA security servers.

TACACS+ vs. RADIUS Protocols

  • TACACS+ separates AAA, provides router command authorization, and encrypts the entire packet with TCP.
  • RADIUS combines authentication and authorization, encrypts only the password via UDP, and has extensive accounting capabilities.

TACACS+ Authentication process

  • The message flow is in its name and password exchange with the TACACS+ server.
  • TACACS+ authentication uses a bidirectional challenge and response.

RADIUS Authentication process

  • RADIUS Authentication packages the username and password.
  • RADIUS authentication uses a unidirectional challenge and response.

Integration With Active Directory

  • RADIUS communicates between clients and Microsoft Windows Server NPS (IAS) AAA server.

Server-Based AAA Authentication

  • AAA can be configured using the CLI on Cisco routers.
  • Troubleshooting server-based AAA authentication can be performed.

Steps for Configuring Server-Based AAA

  • Enable AAA, specify the IP address of the ACS server, and configure the secret key and authentication either the RADIUS or TACACS+ server.

Server-Based AAA Authorization

  • Authentication ensures a device or user is legitimate.
  • Authorization allows or disallows authenticated users access to certain areas and programs.
  • TACACS+separates authentication from authorization
  • RADIUS does not separate authentication from authorization

Introduction to Server-Based AAA Accounting

  • The configuration involves using the CLI to define accounting parameters.

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