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I know in airports, for example, I've connected to their AP, and it pops up a browser window to log in on my device. Is it possible to do so with NodeMCU in lua, or even with c firmware?

mpromonet
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wordsforthewise
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2 Answers2

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This can accomplished by setting the DNS server for a connecting client [via DHCP] to a sort of DNS proxy. It doesn't need to be a fully featured DNS server, it only needs to be able to either return a static DNS answer for any host name query or forward the request to a real DNS server, to resolve host names as usual.

The static answer effectively hijacks web requests at the DNS level, by forging the DNS answer, causing all host names to resolve to the IP address of a local web server. That local web server ignores any Uri details and serves a login prompt for every request. It must also maintain a list of client MAC addresses that have authenticated.

NodeMCU does have a built-in DHCP server, as part of it's built-in WiFi AP, but running both a web and a DNS proxy in ESP8266's limited memory would be a hell of a trick. I think that two of them working cooperatively, interfaced using the SPI bus might be workable... maybe even three of them, one dedicated to maintaining the list of authenticated MACs, expiring them, etc.

Note that the only part of this I have done on an ESP 8266 is some very simple web server functionality, so it's mostly theory. If you try it I'd be very interested in hearing about it. :-)

Mark McGinty
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  • Thanks. I'm trying to use it with my code here: https://github.com/wordsforthewise/ESP-8266_network-connect the other problem I have is that my android phone keeps disconnecting because the network isn't connected to the internet. I think this DNS spoofing would also solve that problem. – wordsforthewise Aug 23 '15 at 02:58
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You might want to try out CaptiveIntraweb project (https://github.com/reischle/CaptiveIntraweb) which is based on NodeMCU.

There is also thread (http://www.esp8266.com/viewtopic.php?f=32&t=3618) on ESP8266 community forum that discusses the solution details.

Ravi Varma Polakonda
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