Home > Articles > Security > Network Security

This chapter is from the book

Defining an Authentication Server

Before configuring an authentication server on Cisco ASA, you must specify AAA server groups. A server group defines the attributes of one or more AAA servers. This information includes the AAA protocol used, IP address of the AAA servers, and other related information. Complete the following steps to accomplish this using ASDM:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Server Groups > AAA Server Groups.
  • Step 2. By default the LOCAL Server group is present in the configuration. To add a AAA server group click on Add.
  • Step 3. The screen illustrated in Figure 6-4 is shown. Enter a server group name under the Server Group field, as illustrated in Figure 6-4. The AAA server group name used in this example is my-radius-group.
    Figure 6-4

    Figure 6-4 Add AAA Server Group Dialog Box

  • Step 4. Select the AAA protocol to be used from the Protocol drop-down list. RADIUS is used in this example; however, you can choose from any of the following server types:
    • RADIUS
    • TACACS+
    • SDI
    • NT Domain
    • Kerberos
    • LDAP
    • HTTP Form
  • Step 5. Several of the parameters in this dialog box depend on the authentication protocol that is used. In this example all the other fields are left with default values. The Accounting Mode field has two options: Simultaneous and Single. When single mode is selected, the Cisco ASA sends accounting data to only one accounting server. To send accounting data to all servers in the group select Simultaneous.
  • Step 6. Depletion is selected in the Reactivation Mode field. The reactivation mode is used to control the behavior when AAA servers fail. When depletion mode is selected in the Cisco ASA, failed servers are reactivated only after all the servers in the group are inactive. If this option is selected you must add a time interval in the Dead Time field. In this example, the default value is configured (10 minutes).

    Alternatively, you can select Timed mode where failed servers are reactivated after 30 seconds of down time.

  • Step 7. The Max Failed Attempts is used to limit the maximum number of failed authentication attempts. The default is 3 attempts.
  • Step 8. Click OK.
  • Step 9. Click Apply to apply the configuration changes.
  • Step 10. Click Save to save the configuration in the Cisco ASA.

Complete the following steps to add the AAA server to the AAA server group that was previously configured:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Server Groups > AAA Server Groups.
  • Step 2. Click on Add under the Servers in the Selected Group (while selecting the group called my-radius-group. The dialog box shown in Figure 6-5 is displayed.
    Figure 6-5

    Figure 6-5 Add AAA Server Dialog Box

  • Step 3. As you see in Figure 6-5, the Server Group my-radius-group is already pre-populated in the screen. Select the interface where the RADIUS server resides, using the Interface Name pull-down menu. In this example, the RADIUS server is reachable through the management interface.
  • Step 4. Enter the AAA server name or IP address under the Server Name or IP Address field. In this example, the RADIUS server's IP address is 172.18.124.145.
  • Step 5. Specify the amount of time (in seconds) that the Cisco ASA waits before timing out the authentication session under the Timeout field. The default value of 10 seconds is used in this example.
  • Step 6. You can specify the port used by the Cisco ASA to communicate to the RADIUS server for authentication purposes. In this example, the default RADIUS authentication port 1645 is entered under the Server Authentication Port field.
  • Step 7. Similarly, you can specify the port used by the Cisco ASA to communicate to the RADIUS server for accounting. In this example, the default RADIUS accounting port 1646 is entered under the Server Accounting Port field.
  • Step 8. The Retry Interval is the amount of time the Cisco ASA waits to retry an authentication attempt, in case the RADIUS server does not respond. The default value of 10 seconds is used in this example.
  • Step 9. Enter the secret key used by the Cisco ASA and the RADIUS server to authenticate each other under the Server Secret Key field. This can be a string of up to 64 characters.
  • Step 10. Enter a case-sensitive password that is common among users who access this RADIUS authorization server via the Cisco ASA under the Common Password field. If you do not use a common password, the user's username is used as the password when accessing the RADIUS authorization server.
  • Step 11. You can optionally specify how the Cisco ASA will handle netmasks received in downloadable ACLs (covered later in this chapter) by selecting any of the following in the ACL Netmask Convert pull down menu:
    • Detect automatically—The Cisco ASA automatically detects a wildcard netmask expression and converts it to a standard netmask.
    • Standard—The Cisco ASA honors the netmask received from the RADIUS server and does not perform any translation from wildcard netmask expressions.
    • Wildcard—The Cisco ASA converts all netmasks to standard netmask expressions.
    The default value (Standard) is used in this example.
  • Step 12. Click OK.
  • Step 13. Click Apply to apply the configuration changes.
  • Step 14. Click Save to save the configuration in the Cisco ASA.

If you are using the command line interface (CLI) to configure the Cisco ASA, specify AAA server groups with the aaa-server command. The syntax of the aaa-server command to specify a new AAA server group and the respective protocol is as follows:

aaa-server server-tag protocol server-protocol

The server-tag keyword is the server group name that is referenced by the other AAA command, and server-protocol is the name of the supported AAA protocol. Example 6-1 shows the different authentication protocols that can be defined within a AAA server group.

Example 6-1. AAA Server Group Authentication Protocols

New York(config)# aaa-server my-radius-group protocol ?
  kerberos  Protocol Kerberos
  ldap      Protocol LDAP
  nt        Protocol NT
  radius    Protocol RADIUS
  sdi       Protocol SDI
  tacacs+   Protocol TACACS+

In Example 6-1, the AAA server group tag is named my-radius-group. After defining the AAA server group with the respective authentication protocol, you are shown the (config-aaa-server) prompt. Example 6-2 shows the commands that are used to accomplish the same tasks that were previously demonstrated for ASDM.

Example 6-2. Configuring the AAA Server Using the CLI

NewYork(config)# aaa-server my-radius-group protocol radius
NewYork(config-aaa-server-group)# aaa-server my-radius-group (management) host
172.18.124.145
NewYork(config-aaa-server-host)#  key myprivatekey
NewYork(config-aaa-server-host)#  radius-common-pw mycommonpassword

In Example 6-2, the AAA server group my-radius-group is defined to process authentication requests using the RADIUS protocol. In the second line the RADIUS server (172.18.124.145) is defined, as well as the interface (management) where the RADIUS server resides. The key used for authentication is myprivatekey. The RADIUS common password is set to mycommonpassword.

You can also use the max-failed-attempts subcommand, which specifies the maximum allowed number of communication failures for any server in the AAA server group before that server is disabled or deactivated. The maximum number of failures can be configured in a range from 1 to 5.

Cisco ASA supports two different AAA server reactivation policies or modes:

  • Timed mode—The failed or deactivated servers are reactivated after 30 seconds of downtime.
  • Depletion mode—The failed or deactivated servers remain inactive until all other servers within the configured group are inactive.

To view statistics about all AAA servers defined for a specific protocol, use the following command:

show aaa-server protocolserver-protocol

Example 6-3 includes the output of this command for the RADIUS protocol.

Example 6-3. Output of the show aaa-server protocol Command

New York# show aaa-server protocol radius
Server Group:    mygroup
Server Protocol: radius
Server Address:  172.18.124.145
Server port:     1645(authentication), 1646(accounting)
Server status:   ACTIVE, Last transaction at unknown
Number of pending requests               0
Average round trip time                  0ms
Number of authentication requests       55
Number of authorization requests        13
Number of accounting requests           45
Number of retransmissions               0
Number of accepts                       54
Number of rejects                        1
Number of challenges                    54
Number of malformed responses           0
Number of bad authenticators            0
Number of timeouts                       0
Number of unrecognized responses        0

Several counters can be helpful when troubleshooting AAA-related problems. For instance, you can compare the number of authentication requests versus the number of authentication rejects and accepts. Additionally, you should pay attention to any malformed authentication requests, unrecognized responses, or timeouts to determine whether there is a communication problem with the AAA server.

To show the configuration of a specific AAA server, use the following command:

show running-config aaa-server [server-group [(if_name) host ip_address]]

To show statistics about a specific AAA server, use the following command:

show aaa-server [server-tag [host hostname]]

Example 6-4 includes the output of this command for server 172.18.124.145.

Example 6-4. Output of the show aaa-server Command for a Specific Host

New York# show aaa-server mygroup host 172.18.124.145
Server Group:    my-radius-group
Server Protocol: radius
Server Address:  172.18.124.145
Server port:     1645(authentication), 1646(accounting)
Server status:   ACTIVE, Last transaction at unknown
Number of pending requests               0
Average round trip time                  0ms
Number of authentication requests       55
Number of authorization requests        13
Number of accounting requests           45
Number of retransmissions               0
Number of accepts                        54
Number of rejects                        1
Number of challenges                     54
Number of malformed responses           0
Number of bad authenticators            0
Number of timeouts                       0
Number of unrecognized responses        0

To clear the AAA server statistics for a specific server, use this command:

clear aaa-server statistics [tag [host hostname]]

To clear the AAA server statistics for all servers providing services for a specific protocol, use this command:

clear aaa-server statistics protocol server-protocol

To erase a specific AAA server group from the configuration, use this command:

clear configure aaa-server [server-tag]

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020