WARNING: IPv4 forwarding is disabled. Networking will not work

vim /etc/sysctl.conf
insert

net.ipv4.ip_forward = 1
wq

/sbin/sysctl net.ipv4.ip_forward   : look if 1 ok  0 is not working

/sbin/sysctl -w net.ipv4.ip_forward=1    :If the above command returns a 1, then IP 
forwarding is enabled. If it returns a 0, 
then you can turn it on manually using the following command: