http://www.opensecurityarchitecture.org/cms/library/icon-library

Our icon library is depicted as PNG images on this page, and as a pack of 
SVG and PNG images in a zip file for download. We have based these icons on 
the Tango Free Desktop Project SVG images (many thanks for the excellent 
base images).

You are free to use these as the basis for building patterns in conjunction 
with the pattern template we provide. If you have ideas for new icons please 
let us know, or send through examples as SVG so we can include in the next 
release. All PNG icons are rendered at 128 x 128 pixels.