iptables 參考
iptables [-t table] command CHAIN [NUM] match criteria -j ACTION CHAIN -N: (new) new a chain -X: delete chain -F: flush all chain -Z: zero the pkg counter -P: policy of chain -E: rename rule -A: append rule -I: insert rule to number -R: replace -D: delete LIST -L: list -S: Specification -n: user number to show -v: verbose -x: show msg –line number: show line number DST-NAT sudo sysctl net.