Managing a Security Group

Security Group (SG) works as a virtual firewall that controls incoming traffic to protect resources hosted in AWS, such as EC2 and RDS, from unwanted access. The same SGs should be associated with services/resources having the same functionality and security requirements such as a cluster of web servers. SGs can span across different subnets in a VPC. SGs are stateful firewalls where you can define rules for a valid source, protocol, and port for incoming and outgoing traffic. Stateful meaning--if the connection from source to destination is allowed, the return path is also allowed. At least one SG needs to be attached to the resource at the time of resource creation. More than one SG can also be attached to a resource. The rules of an SG can be modified at any time and they will take effect immediately. An SG can be detached from the resource at any time.