Cisco Configuring Web-Based Authentication Manual: Comprehensive Guide

Web-Based Authentication Overview

Web-Based Authentication This chapter describes how to configure web-based authentication on the device. It contains these sections: Restrictions for Web-Based Authentication, on page 1 Information About Web-Based Authentication, on page 1 How to Configure Web-Based Authentication, on page 10 Verifying Web-Based Authentication, on page 22 Feature History for Web-Based Authentication, on page 22 Restrictions for Web-Based Authentication A device without host switch virtual interface (SVI) does not intercept TCP SYN packets for Cisco Identity Services Engine (ISE) posture redirection.

Information About Web-Based Authentication Web-Based Authentication Overview Use the web-based authentication feature, known as web authentication proxy, to authenticate end users on host systems that do not run the IEEE 802.1x supplicant. When you initiate an HTTP session, web-based authentication intercepts ingress HTTP packets from the host and sends an HTML login page to the users. The users enter their credentials, which the web-based authentication feature sends to the authentication, authorization, and accounting (AAA) server for authentication.

If authentication succeeds, web-based authentication sends a Login-Successful HTML page to the host and applies the access policies returned by the AAA server. If authentication fails, web-based authentication forwards a Login-Fail HTML page to the user, prompting the user to retry the login. If the user exceeds the maximum number of attempts, web-based authentication forwards a Login-Expired HTML page to the host, and the user is placed on a watch list for a waiting period. HTTPS traffic interception for central web authentication redirect is not supported. Note Web-Based Authentication 1

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Device Roles

Note You should use global parameter-map (for method-type, custom, and redirect) only for using the same web authentication methods like consent, web consent, and webauth, for all the clients and SSIDs. This ensures that all the clients have the same web-authentication method. If the requirement is to use Consent for one SSID and Web-authentication for another SSID, then you should use two named parameter-maps. You should configure Consent in first parameter-map and configure webauth in second parameter-map. Note The traceback that you receive when webauth client tries to do authentication does not have any performance or behavioral impact.

It happens rarely when the context for which FFM replied back to EPM for ACL application is already dequeued (possibly due to timer expiry) and the session becomes ‘unauthorized’. Based on where the web pages are hosted, the local web authention can be categorozied as follows: Internal —The internal default HTML pages (Login, Success, Fail, and Expire) in the controller are used during the local web authentication. Customized —The customized web pages (Login, Success, Fail, and Expire) are downloaded onto the controller and used during the local web authentication. External —The customized web pages are hosted on the external web server instead of using the in-built or custom web pages.

Based on the various web authentication pages, the types of web authentication are as follows: Webauth —This is a basic web authentication. Herein, the controller presents a policy page with the user name and password. You need to enter the correct credentials to access the network. Consent or web-passthrough —Herein, the controller presents a policy page with the Accept or Deny buttons. You need to click the Accept button to access the network. Webconsent —This is a combination of webauth and consent web authentication types. Herein, the controller presents a policy page with Accept or Deny buttons along with user name or password.

You need to enter the correct credentials and click the Accept button to access the network. Device Roles With web-based authentication, the devices in the network have these specific roles: Client —The device (workstation) that requests access to the LAN and the services and responds to requests from the switch. The workstation must be running an HTML browser with Java Script enabled. Authentication server —Authenticates the client. The authentication server validates the identity of the client and notifies the switch that the client is authorized to access the LAN and the switch services or that the client is denied.

Switch —Controls the physical access to the network based on the authentication status of the client. The switch acts as an intermediary (proxy) between the client and the authentication server, requesting identity information from the client, verifying that information with the authentication server, and relaying a response to the client. Web-Based Authentication Device Roles Web-Based Authentication 2

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Authentication Process

Figure 1: Web-Based Authentication Device Roles This figure shows the roles of these devices in a network. Host Detection The switch maintains an IP device tracking table to store information about detected hosts. For Layer 2 interfaces, web-based authentication detects IP hosts by using these mechanisms: • ARP based trigger—ARP redirect ACL allows web-based authentication to detect hosts with a static IP address or a dynamic IP address. • Dynamic ARP inspection • DHCP snooping—Web-based authentication is notified when the switch creates a DHCP-binding entry for the host. Session Creation When web-based authentication detects a new host, it creates a session as follows:

• Reviews the exception list. If the host IP is included in the exception list, the policy from the exception list entry is applied, and the session is established. • Reviews for authorization bypass If the host IP is not on the exception list, web-based authentication sends a nonresponsive-host (NRH) request to the server. If the server response is access accepted, authorization is bypassed for this host. The session is established. • Sets up the HTTP intercept ACL If the server response to the NRH request is access rejected, the HTTP intercept ACL is activated, and the session waits for HTTP traffic from the host.

Authentication Process When you enable web-based authentication, these events occur: • The user initiates an HTTP session. Web-Based Authentication Host Detection Web-Based Authentication 3

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Local Web Authentication Banner

• The HTTP traffic is intercepted, and authorization is initiated. The switch sends the login page to the user. The user enters a username and password, and the switch sends the entries to the authentication server. • If the authentication succeeds, the switch downloads and activates the user’s access policy from the authentication server. The login success page is sent to the user. • If the authentication fails, the switch sends the login fail page. The user retries the login. If the maximum number of attempts fails, the switch sends the login expired page, and the host is placed in a watch list. After the watch list times out, the user can retry the authentication process.

• If the authentication server does not respond to the switch, and if an AAA fail policy is configured, the switch applies the failure access policy to the host. The login success page is sent to the user. • The switch reauthenticates a client when the host does not respond to an ARP probe on a Layer 2 interface, or when the host does not send any traffic within the idle timeout on a Layer 3 interface. • The switch reauthenticates a client when the host does not respond to an ARP probe on a Layer 2 interface. • The feature applies the downloaded timeout or the locally configured session timeout.

• If the terminate action is RADIUS, the feature sends a nonresponsive host (NRH) request to the server. The terminate action is included in the response from the server. • If the terminate action is default, the session is dismantled, and the applied policy is removed. Local Web Authentication Banner With Web Authentication, you can create a default and customized web-browser banners that appears when you log in to a switch. The banner appears on both the login page and the authentication-result pop-up pages. The default banner messages are as follows: Authentication Successful Authentication Failed Authentication Expired The Local Web Authentication Banner can be configured in as follows:

• Legacy mode—Use the ip admission auth-proxy-banner http global configuration command. • New-style mode—Use the parameter-map type webauth global banner global configuration command. The default banner Cisco Systems and Switch host-name Authentication appear on the Login Page. Cisco Systems appears on the authentication result pop-up page. Web-Based Authentication Local Web Authentication Banner Web-Based Authentication 4

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