How do I enable IP forwarding under RHEL / Red Hat / Fedora / CentOS Linux operating systems?
You can easily turn on IP forwarding under Linux operating system by modifying Linux kernel variables (MIB).
Linux Enable IP Forwarding
Open /etc/sysctl.conf file using a text editor, enter:
# vi /etc/sysctl.conf
Set net.ipv4.ip_forward to 1, enter:
net.ipv4.ip_forward = 1
Save and close the file. Reload the changes by typing the following command:
# sysctl -p