We can easily determine whether IP Forwarding is enabled or not to execute the below command if the output will be shown 1 the IP_FORWARED is enabled in your system.

cat /proc/sys/net/ipv4/ip_forward



0

Another method is to check the status,


sysctl -a | grep net.ipv4.ip_forward



net.ipv4.ip_forward = 0

How to Enabled ip_forward:

Open the the sysctl.conf and enable IPforwarding
vim /etc/sysctl.conf



# Controls IP packet forwarding

net.ipv4.ip_forward = 0

change to


net.ipv4.ip_forward = 1

:wq! 

save and quit.

Your changes take effect immediately run a below command
sysctl -p /etc/sysctl.conf

or


sysctl -p



net.ipv4.ip_forward = 1

net.ipv4.conf.default.rp_filter = 1

net.ipv4.conf.default.accept_source_route = 0

kernel.sysrq = 0

kernel.core_uses_pid = 1

net.ipv4.tcp_syncookies = 1

net.bridge.bridge-nf-call-ip6tables = 0

net.bridge.bridge-nf-call-iptables = 0

net.bridge.bridge-nf-call-arptables = 0

kernel.msgmnb = 65536

kernel.msgmax = 65536

kernel.shmmax = 68719476736

kernel.shmall = 4294967296

Save the configuration :
sysctl -w

If you need change the ip forward temporary, execute the command to enable it after every reboot.
echo 1 > /proc/sys/net/ipv4/ip_forward