Captive Portal

The captive portal technique forces an HTTP client on a network to see a special web page (usually for authentication purposes) before using the Internet normally. A captive portal turns a Web browser into an authentication device. This is done by intercepting all packets, regardless of address or port, until the user opens a browser and tries to access the Internet. At that time the browser is redirected to a web page which may require authentication and/or payment, or simply display an acceptable use policy and require the user to agree. Captive portals are used at many Wi-Fi hotspots, and can be used to control wired access (e.g. apartment houses, hotel rooms, business centers, "open" Ethernet jacks) as well.

Since the login page itself must be presented to the client, either that login page is locally stored in the gateway, or the web server hosting that page must be "whitelisted" via a walled garden to bypass the authentication process. Depending on the feature set of the gateway, multiple web servers can be whitelisted (say for iframes or links within the login page). In addition to whitelisting the URLs of web hosts, some gateways can whitelist TCP ports. The MAC address of attached clients can also be set to bypass the login process.

Read more about Captive PortalSoftware Captive Portals, Limitations

Other articles related to "captive portal, captive portals":

Captive Portal - Limitations
... For this reason some captive portal solutions created extended authentication mechanisms to limit the risk for usurpation ... Captive portals require the use of a browser this is usually the first application that users start, but users who first use an email client or other will find the ... and a TCP/IP stack but do not have a web browser that supports HTTPS cannot use many captive portals ...

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