Gnash is a project which aims to create a player and browser plugin for the Adobe Flash file format which is free software, replacing the proprietary software niche currently occupied by Adobe Flash Player.
Gnash requires either of the following - AGG, Cairo, or OpenGL for rendering.
It supports SWF-4 version completely and parts of SWF-8-9 formats
To install Gnash -
sudo apt-get install gnash
sudo apt-get install mozilla-plugin-gnash