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M2M Cellular Gateway
message comes from, check the security key, reply a confirmation SMS to the sender,
deletes the SMS message in the queue and tries to reboot itself.
7.5 Captive Portal
A captive portal is a portal web page that is displayed before a user can browse Internet. The
portal is often used to present a login page. This is done by intercepting most packets, regardless of
address or port, until the user opens a browser and tries to access the web. 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 hotspot
services, 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. This technique has occasionally been referred to as UAM (Universal Access
Method) in implementations and standards forums.
The gateway supports the Captive Portal function to ask guests or passengers to pass the
authentication process before they can surf the Internet via the gateway. There are two approaches,
including internal captive portal and external captive portal. For external captive portal, you must
specify external RADIUS (Remote Authentication Dial In User Service) server and external UAM
(Universal Access Method) server. In contrast, for internal captive portal, you will only select "Internal
RADIUS Server" option for user authentication. The user account database can be an embedded
database, an external AD database or an external LDAP database. However, the UAM server is not
necessary for this case and that the captive portal Web site is embedded in the device.
7.5.1 Configuration
Administrator of gateway can enable the Captive Portal function and configure the device to be
the internal captive portable or the external captive portal for the function. But please be noted that
there is only selected AMIT gateway models support external captive portal function.
15 http://en.wikipedia.org/wiki/Captive_portal
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