Define the term "captive portal" in the context of network access.

A captive portal is a network device or a software application that is used to control access to a network, typically a Wi-Fi network. It serves as a gateway or intermediary between users attempting to connect to the network and the resources or services available on that network. The primary purpose of a captive portal is to authenticate users and enforce specific policies before granting them access to the network.

  1. Authentication and Authorization:
    • When a user connects to a network with a captive portal, the initial access is usually unrestricted. However, the user's traffic is redirected to a captive portal server for authentication and authorization.
    • Users are required to provide credentials, such as a username and password, or agree to terms and conditions to access the network. This process ensures that only authorized users can connect.
  2. Redirection:
    • Upon connection to the network, users are automatically redirected to the captive portal page. This redirection is achieved by intercepting the user's initial request and sending them to the portal.
  3. Web Server:
    • The captive portal typically includes a web server that hosts the authentication and authorization pages. These pages can be customized to display branding, terms of service, login forms, or any other information deemed necessary by the network administrator.
  4. RADIUS Server Integration:
    • In many cases, captive portals integrate with RADIUS (Remote Authentication Dial-In User Service) servers for authentication purposes. RADIUS allows centralized authentication, authorization, and accounting for users attempting to access the network.
  5. Session Management:
    • The captive portal manages user sessions, keeping track of authenticated users and their access privileges. This helps enforce policies such as session timeouts, bandwidth limits, or specific access controls.
  6. Policy Enforcement:
    • The captive portal can enforce various network policies based on user authentication. For example, it may grant different levels of access to users based on their roles or apply specific bandwidth limitations.
  7. Logging and Reporting:
    • Captive portals often log user activity and authentication details for security and auditing purposes. This information can be used to monitor network usage, troubleshoot issues, and generate reports on user behavior.
  8. Customization:
    • Network administrators can customize the appearance and behavior of the captive portal to align with the organization's branding and policies.

A captive portal is a crucial component in securing and managing network access. It plays a pivotal role in authenticating users, enforcing policies, and providing a gateway for users to access the network's resources after meeting the specified criteria.