I run into problems when trying to use the Carnivore library under Linux in a little network sonification project with Processing. The problem turned to be the jpcap library that comes built into the CarnivorePE server and the client library for Processing. The libjpcap.so dynamic library was incompatible with the Linux Mandriva 2008 I have installed on my machine.
So the solution was to grab the latest source code package of jpcap (0.01.16 at this time), and recompile it on my PC. After replacing libjpcap.so by the new one (available here), carnivorePE and the Processing client library started to work fine. However, I had to make two small fixes in the original code of jpcap, see here.