PirateBox

Overview

PirateBox app for YunoHost.

Based on DropCenter (the project was patched in order to remove the authentication mechanism and some other useless features).

Open wifi Access Point (AP)
Once connected to the AP, you can go on http://pirate.box, or http://www.google.com or even http://lqksjdhfkljhsdf.qsdf (or let your captive portal detection mechanism do its job)
All destinations lead to the PirateBox web page
No authentication required for uploading, downloading or deleting (lawless zone)
Of course, works without internet connection
Screenshot

The YunoHost administration is only available through the wired connection.

You have to install the Wifi Hotspot app for YunoHost before and disable the wifi secure access mode thanks to the friendly web interface.

Explanations:

all packets to port 53 are redirected to the port 4253,
a fake DNS resolver listens on the port 4253, and systematically responds the IPv4 address of the server (a fake DNS resolver is mandatory for responding to any requests, without internet connection),
a MASQUERADE rule allows the fake DNS to respond in place of the initially requested resolver,
all packets to port 80 are redirected to the port 4280,
a Nginx vhost listens on the port 4280, and redirects to the PirateBox web page.

IPv4-only because the NAT table is not available for IPv6 before the kernel 3.8 (not in Debian stable for now)
Don't redirect to the PirateBox web page with explicit HTTPS requests (in order to avoid offering self-signed certificates on well-known domains)