要做Sniffer了，先在Linux下编译一下libpcap
1、编译安装flex
#libpcap 1.1要求flex必须在2.4.6及以上
wget http://prdownloads.sourceforge.net/flex/flex-2.5.35.tar.gz?download
tar -xzvf flex-2.5.35.tar.gz
cd flex-2.5.35
./configure --prefix=/usr
make -j
sudo make install[......]