I have created external application load balancer in aws, i need to wirite security group rule to allow traffic from only one private subnet ec2-instance. any suggestions please ?
Private subnet
If a subnet's default traffic is routed to a NAT instance/gateway or completely lacks a default route, the subnet is known as a private subnet. For example, an instance launched in this subnet is not publicly accessible even if it has an Elastic IP address or a public IP address associated with it.
Open your VPC nat IP in ELB security group