The practice of using chalk markings on sidewalks or buildings to alert other geeks to the presence of a wireless IEEE 802.11-compatible network capable of providing Internet access.

Invented in London by Matt Jones, and chronicled at his website,, this system was inspired by a similar chalking system used by hobos during the Great Depression to communicate to others where food and shelter could be found.

In the current system, three basic markings are used to signify whether the network is open, closed, or secured using Wireless Equivalent Privacy. Additional parameters such as the access point's password and bandwidth can be inscribed as well.

Warchalking is similar to the idea of a hobo language, a secret system of marking out things for others versed in the system to find when they are in an unfamiliar place.

It has overtones of geocaching and maybe bookcrossing but its purpose is to promote open wifi nodes.

From an oreilly page, "You've found yourself an open Wireless Lan - and you want to share the you slap it on the web? Well, that's a good idea, except that to find the node, you have to be on the net in the first place. Not much good if you're just off a plane, in a strange city and need to grab your mail.

So why not WarChalk - Matt Jone's hobo-inspired idea for spreading the wireless word.

You find a node, and draw the correct symbol on a nearby piece of public furniture - a wall, the pavement, the side of a lamppost. Anyone knowing in the ways of the WarChalking will recognise what it means, and get online. No more wandering around bandwidthless, and no more struggling with online maps."


Warchalking is a practice used to publicly indicate the presence of a wireless network in an urban area, either public or private. A basic system of symbols are used to describe the type of network ie. bandwidth, open, closed, WEP, SSID, distance and location. There are also more advanced symbols used, such as an eye to indicate logging, but these are not part of the core symbol group. These symbols are drawn on the street by warchalkers to promote the use of free wireless networks and to "enlighten" corporations with lax network security.

War chalking is closely related to war driving and war walking. It claims to have its roots from depression days when hobos would use a system of drawn symbols to indicate a place where a free meal could be obtained, presumably because not all hobos were able to read and write back then. (as opposed to now?)

It's a very cool urban art form in its infancy, set to become huge, with warchalking images popping up in every continent. Many major newspapers and magazines have also devoted many column inches to war chalking and wardriving.

Graffiti for geeks.

PDF of basic war chalking symbols:

The home of warchalking:

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