加载：
modprobe ip_tables
modprobe iptable_filter
modprobe iptable_nat
modprobe ip_conntrack
modprobe ip_conntrack_ftp
modprobe ip_nat_ftp
modprobe ipt_state

查看
lsmod  | grep nat
iptable_nat             6158  0
nf_nat                 22759  1 iptable_nat
nf_conntrack_ipv4       9506  3 iptable_nat,nf_nat
nf_conntrack           79758  3 iptable_nat,nf_nat,nf_conntrack_ipv4
ip_tables              17831  2 iptable_nat,iptable_filter
lsmod  | grep filter
iptable_filter          2793  0
ip_tables              17831  2 iptable_nat,iptable_filter