Make a linux system act as a NAT router for another node

route-to-ip.bash

#!/bin/bash

if [[ $# -ne 1 ]]; then
    echo 'Usage: '"$0"' IP_ADDRESS' >&2
    exit 1
fi

ip="$1"

set -x

sudo iptables -F FORWARD
sudo iptables -P FORWARD DROP

sudo iptables -t nat -F PREROUTING
sudo iptables -t nat -F POSTROUTING

sudo iptables -I FORWARD -i ens2 -o ens2 -m conntrack --ctstate DNAT -j ACCEPT
#sudo iptables -A FORWARD -m conntrack --ctstate NEW,RELATED,ESTABLISHED -d "$ip" -j LOG --log-prefix "Home Gateway "

sudo iptables -t nat -p tcp -I PREROUTING -i ens2 -m multiport --dports 80:42070 -j DNAT --to-destination "$ip"
sudo iptables -t nat -p udp -I PREROUTING -i ens2 -m multiport --dports 80:42070 -j DNAT --to-destination "$ip"

sudo iptables -o ens2 -t nat -I POSTROUTING -d "$ip" -j MASQUERADE

sudo iptables-save | sudo tee /etc/iptables/rules.v4