auto lo
iface lo inet loopback

auto enp2s0
iface enp2s0 inet dhcp
        post-up echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
        post-up iptables -t nat -A POSTROUTING -o enp2s0 -j MASQUERADE
        post-up ip6tables -t nat -A POSTROUTING -o enp2s0 -j MASQUERADE

auto enp0s31f6
iface enp0s31f6 inet dhcp
        post-up echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
        post-up iptables -t nat -A POSTROUTING -o enp0s31f6 -j MASQUERADE
        post-up ip6tables -t nat -A POSTROUTING -o enp0s31f6 -j MASQUERADE
