This is a document from 2005. Quite old you may think but the techniques described there still work today. In the meantime, after four years, there is still no real remedy to stop people conducting such kind of attacks. DDos, SYN flooding and smurf attacks are still a problem.
Also because there is some code in the “External code” section which allows to conduct such attacks it’s good to know what it is, what it does, how it does it and how it looks like when it does it.

Read it here.