Learn about the key characteristics of security groups in Amazon Web Services (AWS), including how they provide stateful firewall protection for EC2 instances. Discover how security groups differ from traditional firewalls and the benefits they offer for securing your cloud resources.
Table of Contents
Question
Which statement about security groups is true?
A. Security groups are stateful.
B. Security groups can be used on only one instance at a time.
C. Security groups are stateless.
D. Security groups can be used to block suspicious IP addresses.
Answer
A. Security groups are stateful.
Explanation
Security groups are stateful, which means that for every inbound rule, an outbound response is allowed, even if you don’t configure one. Conversely, for every outbound rule, an inbound response is allowed, even if you don’t configure one.
Security groups in Amazon Web Services (AWS) act as virtual firewalls for EC2 instances, controlling inbound and outbound traffic at the instance level. They are stateful, which means that they automatically allow the return traffic for outbound requests. When you create an inbound rule allowing traffic from a specific source, the security group automatically creates an outbound rule to allow the return traffic.
This stateful behavior simplifies the management of security groups compared to traditional stateless firewalls. With stateless firewalls, you would need to create separate inbound and outbound rules to allow the desired traffic.
Some additional key points about security groups:
- Security groups can be associated with multiple instances, not just one at a time. You can create a security group and apply it to multiple EC2 instances that require the same security settings.
- Security groups do not provide the ability to block specific IP addresses that are considered suspicious. For more advanced IP-based filtering and protection against threats like DDoS attacks, you would need to use other AWS services like Network ACLs or AWS WAF.
- By default, a security group denies all inbound traffic and allows all outbound traffic. You must explicitly add rules to allow the desired inbound traffic.
So in summary, security groups provide a stateful, instance-level firewall for EC2 instances in AWS, simplifying security management compared to traditional stateless firewalls. They can be associated with multiple instances but do not have the capability to block specific suspicious IP addresses.
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