Captive portals are authentication gateways that control access to a network, commonly used in public Wi-Fi hotspots, corporate environments, and paid Wi-Fi services. These portals ensure that users comply with specific terms before gaining internet access. When a user connects, their browser is redirected to the captive portal, which may require authentication, agreement to terms, or even payment before granting internet access

Common Use Cases of Captive Portals:

Captive portals serve as a controlled gateway for users accessing a network. They are widely used in different environments to regulate internet access, enforce policies, and enhance security. Below are some of the most common use cases:

• Public Wi-Fi (Hotels, Airports, Cafes, Shopping Malls) – To control and monitor access.
• Corporate Networks and Enterprises– To enforce access policies.
• Paid Wi-Fi Services – To collect payments before granting internet access.

How Captive Portals Work?

1. Connection

When a user connects to a Wi-Fi network, whether open or encrypted, their device requests an IP address from the network's DHCP server. This allows the device to communicate with the local network but not necessarily access the internet.

2. Redirection to Captive Portal

Once connected, if the user tries to access any website, their request is intercepted by the network gateway. Instead of reaching the intended site, the network redirects the user to a captive portal page. This is done using DNS hijacking or HTTP interception techniques.

3. Authentication and User Agreement

At this stage, the user must complete one of the following actions to gain network access:

• Login with credentials – In enterprise or university networks, users may need to enter a username and password.
• Accept terms and conditions – In public Wi-Fi setups, simply agreeing to terms may be sufficient.
• Enter a voucher or access code – Some networks issue temporary access codes to limit usage.