When using public wireless it needs you to sign in and from what I've gathered it allows you to have access to the internet and provides you with your own network and is not shared with any other devices on the same wireless access point, does anyone know how this could be done and what its called?
closed as unclear what you're asking by Eric G, Xander, Stephane, M'vy, Dog eat cat world May 8 '15 at 7:45
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You mention two distinct technologies: an access portal and client isolation.
In comments you say you are not talking about the access portal part, but rather client isolation.
Most consumer and corporate access points and wireless controllers I have touched have this feature. It is simply built-in to the hardware you are working with, usually a checkbox item. Often this can take the form of a Virtual Access Point which operates at the data link layer (EDIT: See J Kimball's answer for more on VAP).
If you are running a custom AP you might be able to accomplish this with iptables rules, but I can't really speak to that effect.
Is this the type of behavior you are referring to?
What is a VAP?
Every VAP appears as an independent AP to the client. The VAPs emulate the operations of a physical AP at the MAC level. All wireless management traffic that would be transmitted by one physical AP is also transmitted by the VAP. For example, a single physical AP might broadcast 3 SSIDs (using virtual APs). This AP would also transmit the management traffic of 3 independent APs, one for each supported VAP. Improve Air Quality by Minimizing SSIDs:Using Role-Based Access to Increase Wi-Fi Application Performance