How to Enable/Disable IP forwarding in Linux
Setting
echo 'net.ipv4.ip_forward = 1' | sudo tee -a /etc/sysctl.d/99-ipforward.conf
echo 'net.ipv6.conf.all.forwarding = 1' | sudo tee -a /etc/sysctl.d/99-ipforward.conf
sudo sysctl -p /etc/sysctl.d/99-ipforward.conf
or
sysctl -w net.ipv4.ip_forward=1
sysctl -w net.ipv6.conf.all.forwarding=1
Verify
cat /proc/sys/net/ipv4/ip_forward
cat /proc/sys/net/ipv6/conf/all/forwarding