Content filtering
Various types of content can break your anonymity. Freenet filters several content types, and warns the user on all others. For example, we filter HTML, PNGs, GIFs and JPEGs. We also check for RSS, because browsers will usually recognise it in anything. The purpose of filtering is to:
1) Remove (or replace) any dangerous content: links to the web, inline images.
1) Remove any dangerous scripting: scripts can generally create dangerous content.
1) Verify that the content is of the MIME type that it claims to be. If it's not, it might be interpreted by the browser as something else.
1) Remove anything we don't understand.