However, if a login page is presented by a captive portal then the word Success will not be present and iOS will realize that the network connection has been hijacked by a captive portal and will present a browser window allowing the user to login or register.Īpple hosts a number of these pages such that should one of these pages go down, a number of fallbacks can be checked to determine whether connectivity is present or whether our connection is blocked by the presence of a captive portal. If on downloading this small HTML page iOS finds that it contains the word Success as above then it knows that Internet connectivity is available. Each endpoint hosts a small HTML page of the form: Success Success In order to detect a that it has connected to a Wi-Fi network with a captive portal, iOS contacts a number of endpoints hosted by Apple - an example being.
The user must then register or provide login credentials via a web browser in order to be granted access to the network using RADIUS or another protocol providing centralized Authentication, Authorization, and Accounting ( AAA). This protocol defines the Smart Client to Access Gateway interface describing how to authenticate users accessing public IEEE 802.11 (Wi-Fi) networks using the Universal Access Method in which a captive portal presents a login page to the user.
IOS adopts a protocol called Wireless Internet Service Provider roaming ( WISPr 2.0) published by the Wireless Broadband Alliance. So how do we go about ensuring that our app has true Internet connectivity? As it turns out iOS already has a solution to this problem. This in turn may translate to poor reviews on the App Store. Meanwhile, attempts made by your app to retrieve data from the Internet will fail. This can result in confusion as your app will behave as though it is online whilst connected to such a hotspot since Reachability checks will indicate the presence of a Wi-Fi connection. Reachability under these circumstances will return a response indicating that Wi-Fi is available even though true Internet connectivity is in fact unavailable. The device will appear to have connected to a Wi-Fi network but any request for data will fail until the user has agreed to the Wi-Fi hotspot’s terms of service or registered as a new user - depending on the requirements of the hotspot. However Reachability cannot actually detect whether connectivity is present, only that an interface is available that might allow a connection.Ĭonsider the case of an app user making use of a public Wi- Fi hotspot which requires the user to register or agree to terms of service via a captive portal prior to Internet connectivity being established e.g. In iOS development, the de facto means of detecting Internet connectivity has been to make use of Apple’s Reachability sample code.
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