不仅介绍了基本的命令行参数和背后的含义，还说明了这个package运行的前置条件：别忘了设置：
#--------------------------------------------------------------- # Load the NAT module # # Note: It is best to use the /etc/rc.local example in this # chapter. This value will not be retained in the # /etc/sysconfig/iptables file. Included only as a reminder. #--------------------------------------------------------------- modprobe iptable_nat #--------------------------------------------------------------- # Enable routing by modifying the ip_forward /proc filesystem file # # Note: It is best to use the /etc/sysctl.conf example in this # chapter. This value will not be retained in the # /etc/sysconfig/iptables file. Included only as a reminder. #--------------------------------------------------------------- echo 1 > /proc/sys/net/ipv4/ip_forward