I need to evaluate what is out there in regards to network simulation and modeling software. I am especially interested in freeware that will run on Linux. However, just about any application will do. I will compile a list of all the responses I get and will be publishing a web page with this info (part of a larger research project I am doing). I need software that will allow me to see how different applications react to different network/protocols conditions. I would like to create a system that would allow any application to be tested in a controlled environment.