iptable 重置
# 重置 filter table.
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
# 重置 nat table.
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
iptables -t nat -P OUTPUT ACCEPT
# 重置 mangle table.
iptables -t mangle -P PREROUTING ACCEPT
iptables -t mangle -P OUTPUT ACCEPT
# 重新整理 filter and nat tables.
iptables -F
iptables -t nat -F
iptables -t mangle -F
# 清空 all chains in filter and nat table.
iptables -X
iptables -t nat -X
iptables -t mangle -X