Create /etc/sysctl.d/ip-forward.conf and add the following line:
net.ipv4.ip_forward = 1
Verify that the IP forwarding has been applied.
Run the following command:
sudo sysctl --system
Confirm that the command output contains the following line:
net.ipv4.ip_forward = 1
Add firewall rules to accept VRRP communication by using the multicast IP address
224.0.0.18 and the VRRP protocol (112) on each network
interface that Keepalived controls.
For example, run the following commands on each server: