sysctl -w net.ipv4.ip_forward=1
echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf

iptables -t nat -A PREROUTING -p tcp --dport 8080 -j DNAT --to-destination 192.168.1.100:80
iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -A FORWARD -p tcp --dport 80 -j ACCEPT

iptables -t nat -A PREROUTING -p tcp --dport 8080 -j REDIRECT --to-port 80

iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o eth0 -j MASQUERADE

// forwarder.json
{
    "listen": "0.0.0.0:8080",
    "routers": [{"from": "0.0.0.0/0", "to": "192.168.1.100:80"}]
}

80km-forwarder -config forwarder.json