為了更好的學習tcp協議原理，決定安裝tcpdump觀察

準備工具
1. flex 
yum -y install flex
2. bison

wget http://www.tcpdump.org/release/libpcap-1.5.3.tar.gz  
wget http://www.tcpdump.org/release/tcpdump-4.5.1.tar.gz  
tar -zxvf libpcap-1.5.3.tar.gz  
cd libpcap-1.5.3  
./configure  
sudo make install  
  
cd ..  
tar -zxvf tcpdump-4.5.1.tar.gz  
cd tcpdump-4.5.1  
./configure  
sudo make install