iptables forward

iptables_forward.txt

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.0.0/24 -j MASQUERADE
iptables -t nat -A PREROUTING -i eth0 -d 192.168.1.36 -p tcp --dport 8080 -j DNAT --to-destination 192.168.0.36:80

Other Commands:
===============

iptables -F
iptables -F -t nat
iptables -S
iptables -L
iptables -L -t nat

https://wiki.alpinelinux.org/wiki/Configure_Networking#Install_iptables.2Fip6tables

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echo 0 > /proc/sys/net/ipv4/ip_forward
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP
iptables -A FORWARD -i eth1 -o eth0 -s 192.168.0.0/24 -j ACCEPT
iptables -A FORWARD -i eth0 -o eth1 -p tcp --dport 80 -j ACCEPT
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination 192.168.0.36
echo 1 > /proc/sys/net/ipv4/ip_forward


rc-update add iptables 
/etc/init.d/iptables save
/etc/init.d/networking restart



http://linux-training.be/networking/ch14.html
https://wiki.alpinelinux.org/wiki/Configure_Networking