added tcpdump primitive
added tcpdump primitive

added tcpdump primitive that interfaces with the tcpdump process
via the command module. This module implements a parser for some
of tcpdump's command line output and allows for the application of
simple post processing filters after the capture is complete (this
is advised to reduce PII)

iclab/centinel,rpanah/centinel,JASONews/centinel,lianke123321/centinel,ben-jones/centinel,iclab/centinel,rpanah/centinel,lianke123321/centinel,rpanah/centinel,lianke123321/centinel,iclab/centinel,Ashish1805/centinel