War Chalking

'War chalking' (aka 'warchalking') is a method used to advertise the presence of a wireless network with the use of symbols drawn in chalk. The idea of war chalking originated from 'Matt Jones', a web designer who detailed, via his web blog, three possible symbols which could be used to highlight the accessibility of wireless networks. The symbols designed by Matt Jones were inspired and created in the style of 'hobo' symbols used by American travelers during the 1920's and 30's. Below, 'Image 1' shows the symbols devised by Mat Jones which were posted by him on his blog.

Details of the three war chalking symbols shown above are described below:

Open Node

An 'open node' indicates an open network (uses open authentication), where No WEP key is required in order to access the network. Open nodes are indicated by 'two back-to-back semicircles' and the networks SSID, the SSID being located above the symbols. If known, the speed of the connection is indicated below the symbols.

Closed Node

A 'closed node' refers to a wireless network (when the term is used in conjunction with war chalking) 'that can not receive inbound connections'. Closed nodes are indicated wit the use of a circle and the networks SSID, the SSID being located above the drawn circle.

WEP Node

A 'WEP node' refers to a wireless network where a WEP key (uses shared-key authentication) is needed in order to access the network. WEP nodes are indicated with the use of a circle enclosing a 'W' on the centre to indicate its WEP node status. WEP nodes, as with open nodes have the networks SSID indicated above the symbol as well as the connection speed indicated below. Some WEP nodes, when voluntarily war chalked, include contact details of whom to contact in order to gain the WEP key to access the network.

There are however dangers which the presence of these markings can highlight in relation to a wireless network and its security. As well as advertising the availability of a wireless network, it could also inadvertently advertise to a hacker or an email spammer, a possible Internet entry point for illegal activities. In relation to email spammers, open node wireless networks could be used to mass mail millions of unwanted email messages without the Internet connection trail pointing back to the spammer. Below, 'Image 2' shows how a war chalking symbol could look if drawn on a businesses wall whilst 'Image 3' shows how it could be interpreted.



To a wireless network user, the symbols could be interpreted as..



To help protect against war chalking and having a wireless network being advertised, many actions and precautions can be taken. These include the following:

Searching for 'rogue access points'

Please refer to the section entitled 'Rogue AP'.

Prevent the broadcasting of the networks 'SSID'

This would prevent the average computer from detecting the wireless network as the SSID would not be broadcast by the wireless device.

Use WEP encryption (as a minimum!)

This would prevent the most computer users from accessing the network. Please refer to the section entitled 'WEP'.

Secure login method to the local area network (LAN)

This would prevent anyone on gaining access to the network, from being able to access any files which are securely stored on the network. This may not prevent Internet access from being attained.