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Offline networking: Difference between revisions
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Offline and off-grid networking broadly refers to the practice of sharing information between devices without use of the global Internet. The advantage of this in a disaster scenario is to provide a fallback for access to critical information and communication services in cases where reaching the Internet is not possible. This can be done with a device acting as a WiFi access point and router, LoRaWAN devices sharing information over long distances using the LoRa radio specification, or with a digital radio service known as ''packet radio''. Each of these will be covered here. | Offline and off-grid networking broadly refers to the practice of sharing information between devices without use of the global Internet. The advantage of this in a disaster scenario is to provide a fallback for access to critical information and communication services in cases where reaching the Internet is not possible. This can be done with a device acting as a WiFi access point and router, LoRaWAN devices sharing information over long distances using the LoRa radio specification, or with a digital radio service known as ''packet radio''. Each of these will be covered here. | ||
== WiFi == | |||
WiFi (or Wi-Fi) refers to a collection of wireless protocols from the 802.11 collection of standards. WiFi is predominantly used for low power, short range networking, and centers around 2 popular bands, 2.4GHz and the faster 5GHz<ref>https://en.wikipedia.org/wiki/Wi-Fi</ref>. In 2019, it was found more than 3.05 billion Wi-Fi-enabled devices are shipped globally each year<ref>https://www.researchandmarkets.com/reports/5135535/global-wi-fi-enabled-devices-shipment-forecast</ref>. Each of these devices can connect to any wireless access point which is open, or for which they are authenticated. This presents a significant opportunity for the distribution of critical information where Internet access is otherwise not available. | |||
=== Offline WiFi access points === | |||
Due to our habitual relationship with WiFi and connecting to the public Internet, we can often overlook WiFi's applications in 'offline' contexts. A a WiFi access point (AP) does not need the public Internet to provide access to content, if the content is locally accessible to the AP. In such applications, either the WiFi router itself holds the data (perhaps on a USB stick), or the data is served from another device connected directly to the AP. 'Captive portal' wireless access points are those whereby connecting to the | |||
Some commercial routers provide ability for file sharing across their network using the factory firmware installed on the device. However in the majority of applications, ''an after market firmware'' is used, like OpenWrt<https://openwrt.org</ref>. OpenWrt is an open source project and community dedicated to writing and testing firmware that can be 'flashed' onto scavenged or bought WiFi routers, providing them with new functionality and customisation options. At the time of writing, 2043 wireless access points are supported by OpenWrt to some degree<ref>https://openwrt.org/toh/start</ref>. | |||
Many projects have been done exploring the practical application of offline networking in a wireless context using OpenWrt. However, many small form-factor computers can be repurposed as WiFi access points, that either route through to another network (like the Internet) or remain hermetic. | |||
One such project is SubNodes, by Berlin-based artist Sarah Grant, employing Raspberry Pi minicomputers as wireless access points, serving a website and chat application <ref>http://subnodes.org/</ref>. Smartphones, for instance, can be used to connect to the access point, from which is served a website, alongside simple chat application. The project provides complete instructions requiring minimal prior knowledge for deploying a 'SubNode'. Such 'SubNodes' could be employed inside weatherproof plastic cases, like tupperware or a plastic lunchbox, powered off solar power bank, and used to provide valuable information without need for the Internet. | |||
For those more technically inclined, any GNU/Linux laptop or device with a wireless network adapter can be repurposed as a wireless access point serving information and files from a locally hosted website. A popular webserver for use in such contexts is ''lighttpd''. A popular daemon/service providing access point functionality is ''hostapd'', often coupled with ''dnsmasq'' to provide automatic network configuration of clients using the DHCP protocol alongside domain name resolution<ref>https://w1.fi/hostapd/</ref><ref>https://dnsmasq.org/</ref>. | |||
== Linkdump == | == Linkdump == | ||