Simple Application Server has built-in firewalls which opens ports 22, 80, and 443 by default, and closes others. You can configure which ports to open.
Simple Application Server uses VPC by default, and all instances of one user are deployed in one VPC, which guarantees an isolated networking environment of each user.
For now, one user’s cloud products on different VPCs cannot be connected. For example, your Simple Application Server cannot access your RDS on another VPC.