Data Transfer Control

I have UBUNTU 12.04 LTS OPERATING SYSTEM installed in my laptop. I opened one port. I need the following I wish to limit 1 mb data transfer from O.S. to internet. Flexibility to change 1 mb should be provided inside the source code itself. The above should be written in either C or C++ language only. Source code should be given and compilation procedure and how to execute should also be provided and where to keep the executable file should be indicated. Is it necessary to execute after every restart of laptop.