How to build a captive Wi-Fi portal

[Kingfisher]

Hello,
I want to make small network an i experimenting more to make a small captive (wifi) portal system. I have been looking into authpf and it is a pretty
good fit for what i need... but the users won't be SSHing to get allowed. How do captive portals work? Any suggestion??

[Spyrus]

Whenever you go to Wi-Fi hotspot and find a wireless or wired, but instead of getting your homepage when you bring your browser, you get a customized page service provider asking you to pay for service. You've hit a captive portal, and thus the service provider makes sure they are paid for what they are offering.he technology is relatively simple, because you are, by definition using their network. They configure their systems to accept traffic from your original network (in this case, your request for Web content from the server of your homepage), but instead of passing along this request, they send you to their sign-in page.So, to summarize, the captive portal provider needs: a mechanism for redirecting Web traffic, a mechanism for blocking any traffic (firewall, 802.1x, etc.) to force a sign in this facility, a payment gateway of some sort, and some form of identity repository for keeping track of who is a known customer paid and who is not.

[Snake08]

The captive portal technique apply an HTTP client on a network to see a special web page.A captive portal convert a Web browser in a device authentication. [1] 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 in May that require authentication and / or payment, or simply display an acceptable use policy and the user agree. Captive portals are used in most Wi-Fi hotspots, and can be used to control wired access (eg apartment buildings, hotel rooms, business centers, "open" Ethernet jacks) as well . Even when a simple captive portal is used in a free public network access, some people may repeatedly connect using the network on a nearly continuous basis for downloading music, videos or other large files. This activity, called monopolizing the bandwidth can be minimized by additional programs in the captive portal. Such programming can control the speed at which large files are uploaded to limit the size (in kilobytes or megabytes) of files that can be downloaded, restrict the number of downloads that can occur in one session, Login or block Web sites frequently used for downloading large files. This is called the bandwidth or traffic shaping.

[Shen]

Windows-based Wi-Fi hotspot management software (sometimes also known as hotspot software, hotspot access controller or wireless gateway) designed to monitor and secure your Wi-Fi hotspots or visitor-based networks centrally. Based on captive portal technology, FirstSpot ® lets your hotspot users to connect through a web browser.
FirstSpot ® is all about ease of use and gives you unprecedented control over your hotspots. Compare offers from management to other hotspot FirstSpot Windows ®-based architecture and server-based pricing gives you more flexibility in structuring your hotspot access plan. Instead of simply offering free Wi-Fi, building Wi-Fi hotspots quickly became an important corporate image exercise.
FirstSpot ® is the leading Windows based software hotspot in the world and has been deployed in over 45 countries worldwide. With over 1,000 customers, they come from various industry segments including hotels, cafes, ISPs, Internet cafes, libraries, law firms, governments, military, and more.
Different modes of authentication - username and password, Scratch code (for example, simply enter a unique number or login text) (new!), Anonymous (ie just click OK Welcome to the portal to start surfing), Multiple connections (through shared secret) and RADIUS support.