VPC (Virtual Private Cloud) is a private network that allows you to deploy your resources. With VPC we need to know some concepts. They are like this:
- Subnets: allow us to partition our network inside our VPC. Two different types of subnets are we can be mentioned about it.
- Public Subnet: This type of subnet is accessible over the internet
- Private Subnet: Unlike the Public Subnets these ones are not accessible over the internet.
- Route Table: It allows us to define routing between the internet and subnets
- Internet Gateway: It helps VPC instances to connect with the Internet. It can be both way connection internet to subnet and subnet to internet
- NAT Gateway: They are separated by management types like Self( NAT Instances) and AWS-Managed (NAT Gateway). An important point is thanks to NAT, Private subnets are available to access the internet while remaining private. It is one way connection subnet to internet.
- Network Access Control List (NACL):
- It is a firewall which controls traffic from and to subnets.
- Can ALLOW and DENY rules
- Rules include only IP addresses.
- NACL is attached at the Subnet level
- Security Groups:
- It is a firewall that controls traffic to and from Elastic Network Interface (ENI)/ EC2 instance
- Can have only ALLOW rules
- Rules include IP addresses and other security groups
- VPC Flow Logs:
- Capture information about IP traffic going into your interfaces
- Helps to monitor and kind of connectivity issues like subnet to subnet, internet to subnet or subnet to the internet.
- Also allows us to capture network information from AWS-managed interfaces. Like ElastiCache, Elastic Load Balancers, Aurora, RDS etc.
- VPC Flow logs data can be reachable S3, Kinesis and CloudWatch too.
- VPC Peering:
- It allows us to connect two VPCs each others
- Their IP addresses must not be overlapped
- VPC Peering Connection is not transitive in case of more than three VPC etc. Each VPC peering must be set between all pairs
- VPC Endpoints:
- They are extremely important. It allows us to connect AWS services privately without going to public www network
- It enhances the security and decreases the latency to reach the AWS services
- VPC Endpoints for S3 and DynamoDB rest of the services VPC Endpoint Interface
- Only used within your VPC
- Site-to-Site VPN: It allows connection of an On-Premise VPN to AWS on the internet publicly (Connection is encrypted)
- Direct Connect: Establishing a physical connection between AWS and on-premises. Even connection is private, fast and secure, the connection takes at least a month.