Home > Articles > Security > Network Security

This chapter is from the book

Configuring Authentication of Administrative Sessions

Cisco ASA supports authentication of administrative sessions by using a local user database, a RADIUS server, or a TACACS+ server. An administrator can connect to the Cisco ASA via

  • Telnet
  • Secure Shell (SSH)
  • Serial console connection
  • Cisco ASA Device Manager (ASDM)

If connecting via Telnet or SSH, the user can retry authentication three times in case of user error. After the third time, the authentication session and connection to the Cisco ASA are closed. Authentication sessions via the console prompt the user continuously until the correct username and password are entered.

Before you start the configuration, you must decide which user database you will use (local or external AAA server). If you are using an external AAA server, configure the AAA server group and host as covered in the previous section. You can use the aaa authentication command to require authentication verification when accessing Cisco ASA for administration. The following sections teach you how to configure external authentication for each type of connection.

Authenticating Telnet Connections

You can enable Telnet access to the Cisco ASA to any internal interface or to the outside if an IPSec connection is established. (Telnet sessions are allowed to the outside interface only over an IPSec connection.) To configure authentication for Telnet connections to the Cisco ASA using ASDM, complete the following steps:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Access > Authentication. The screen illustrated in Figure 6-6 is displayed.
    Figure 6-6

    Figure 6-6 Using ASDM to Configure Authentication for Telnet Connections

  • Step 2. Select Telnet under the Require Authentication for the Following Types of Connections section.
  • Step 3. In this example, the RADIUS server previously configured in the AAA server group is used for authentication. Select the server group (my-radius-group) from the Server Group pull-down menu.
  • Step 4. If you would like to fall back to the local user database in case the RADIUS server fails, select Use LOCAL when Server Group Fails, as shown in Figure 6-6.
  • Step 5. Click OK.
  • Step 6. Click Apply to apply the configuration changes.
  • Step 7. Click Save to save the configuration in the Cisco ASA.

You can also authenticate any users before they use the enable command via the CLI. To accomplish this task, complete the following steps:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Access > Authentication.
  • Step 2. Select the Enable check box under the Require Authentication to Allow Use of Privilege Mode Commands section, as shown in Figure 6-6.
  • Step 3. In this example, the RADIUS server is used for authentication. Select the server group my-radius-group from the Server Group drop-down list.
  • Step 4. To allow the Cisco ASA to use the local database as a fallback method, select the Use LOCAL when Server Group Fails check box.
  • Step 5. Click OK.
  • Step 6. Click Apply to apply the configuration changes.
  • Step 7. Click Save to save the configuration in the Cisco ASA.

Example 6-5 shows the CLI commands sent by ASDM to the Cisco ASA.

Example 6-5. Using the CLI to Configure Authentication for Telnet Connections

aaa authentication enable console my-radius-group LOCAL
aaa authentication telnet console my-radius-group LOCAL
telnet 0.0.0.0 0.0.0.0 inside

In Example 6-5, the aaa authentication enable console command is set to require authentication before any user can enter into enable mode. The my-radius-group AAA server group name is applied to this command. The keyword LOCAL is used to enable fallback to the local database if the configured authentication server is unavailable.

The second line in Example 6-5 enables authentication for Telnet connections by using the my-radius-group AAA server group, as well as the LOCAL keyword to enable fallback to the local database.

Authenticating SSH Connections

The steps for using ASDM to configure authentication for SSH administrative sessions to the Cisco ASA are very similar to the ones discussed in the previous section. Complete the following steps to configure authentication for SSH connections to the Cisco ASA:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Access > Authentication. The same screen illustrated in Figure 6-6 is displayed.
  • Step 2. Select SSH under the Require Authentication for the Following Types of Connections section.
  • Step 3. In this example, the RADIUS server previously configured in the AAA server group (my-radius-group) is used for authentication.
  • Step 4. If you would like to fall back to the local user database in case the RADIUS server fails, select Use LOCAL when Server Group Fails, as shown in Figure 6-6.
  • Step 5. Click OK.
  • Step 6. Click Apply to apply the configuration changes.
  • Step 7. Click Save to save the configuration in the Cisco ASA.

To enable SSH on Cisco ASA via the CLI, you first configure a hostname and domain name before generating the RSA key pair used by SSH. Example 6-6 shows how to generate the RSA key pair and enable SSH version 2 connections from any systems on the inside interface.

Example 6-6. Generating RSA Key Pair and Enabling SSH Version 2

New York# configure terminal
New York(config)# hostname ASA
New York(config)# domain-name cisco.com
New York(config)# crypto key generate rsa modulus 2048
INFO: The name for the keys will be: ASA.cisco.com
Keypair generation process begin.
New York(config)# ssh 0.0.0.0 0.0.0.0 inside
New York(config)# ssh version 2

After the RSA key pair has been generated and SSH has been enabled, complete your AAA server group and host configuration. In this example, the my-radius-group AAA server group is used in the aaa authentication ssh console command to enable SSH authentication, as shown in Example 6-7.

Example 6-7. Configuring SSH Authentication to a TACACS+ Server

New York(config)# aaa authentication ssh console my-radius-group LOCAL

The LOCAL keyword is used in Example 6-7 to enable fallback to the local database. Make sure to issue the write memory command to save the configuration after the RSA keypair is generated.

Authenticating Serial Console Connections

Complete the following steps to configure authentication for serial console connections to the Cisco ASA, using ASDM:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Access > Authentication.
  • Step 2. Select Serial under the Require Authentication for the Following Types of Connections section.
  • Step 3. In this example, the RADIUS server previously configured in the AAA server group (my-radius-group) is used for authentication.
  • Step 4. If you would like to fall back to the local user database in case the RADIUS server fails, select Use LOCAL when Server Group Fails.
  • Step 5. Click OK.
  • Step 6. Click Apply to apply the configuration changes.
  • Step 7. Click Save to save the configuration in the Cisco ASA.

To configure authentication of serial console connections, use the aaa authentication serial console command. Be aware that you can get locked out of the Cisco ASA easily with any misconfiguration. Example 6-8 demonstrates how to configure serial console authentication, using the AAA server group previously configured.

Example 6-8. Configuring Serial Console Authentication

New York(config)# aaa authentication serial console my-radius-group LOCAL

Authenticating Cisco ASDM Connections

Complete the following steps to configure authentication for ASDM administrative connections to the Cisco ASA using ASDM:

  • Step 1. Log in to ASDM and navigate to Configuration > Device Management > Users/AAA > AAA Access > Authentication.
  • Step 2. Select HTTP/ASDM under the Require Authentication for the Following Types of Connections section.
  • Step 3. In this example, the RADIUS server previously configured in the AAA server group (my-radius-group) is used for authentication.
  • Step 4. If you would like to fall back to the local user database in case the RADIUS server fails, select Use LOCAL when Server Group Fails.
  • Step 5. Click OK.
  • Step 6. Click Apply to apply the configuration changes.
  • Step 7. Click Save to save the configuration in the Cisco ASA.

Alternatively, the aaa authentication http console CLI command can be configured to require authentication for Cisco ASDM users. Example 6-9 demonstrates how to configure ASDM authentication, using the AAA server group previously configured.

Example 6-9. Configuring HTTP Authentication for ASDM Users

New York(config)# aaa authentication http console my-radius-group LOCAL

If this command is not configured, Cisco ASDM users can gain access to the ASA by entering only the enable password, and no username, at the authentication prompt.

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