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.
Other articles related to "captive portal, captive portals":
... 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 ...
Famous quotes containing the words portal and/or captive:
“Little scavenger away,
touch not the door,
beat not the portal down.”
—Hilda Doolittle (18861961)
“My Vanquisher, spoild of his vanted spoile;
Death his deaths wound shall then receive, & stoop
*nglorious, of his mortall sting disarmd.
I through the ample Air in Triumph high
Shall lead Hell Captive maugre Hell, and show
The powers of darkness bound. Thou at the sight
Pleasd, out of Heaven shalt look down and smile,”
—John Milton (16081674)