Amazon Virtual Private Cloud (VPC)

A variety of connectivity options exist for your Amazon Virtual Private Cloud. You can connect your VPC to the Internet, to your datacenter, or other VPC's, based on the AWS resources that you want to expose publicly and those that you want to keep private.

• Connect directly to the Internet (public subnets)– You can launch instances into a publicly accessible subnet where they can send and receive traffic from the Internet.
• Connect to the Internet using Network Address Translation (private subnets)– Private subnets can be used for instances that you do not want to be directly addressable from the Internet. Instances in a private subnet can access the Internet without exposing their private IP address by routing their traffic through a Network Address Translation (NAT) gateway in a public subnet.
• Connect securely to your corporate datacenter– All traffic to and from instances in your VPC can be routed to your corporate datacenter over an industry standard, encrypted IPsec hardware VPN connection.
• Connect privately to other VPCs- Peer VPCs together to share resources across multiple virtual networks owned by your or other AWS accounts.
  
• Connect to Amazon S3 without using an internet gateway or NAT, and control what resources, requests, or users are allowed through a VPC endpoint.
  
• Combine connectivity methods to match the needs of your application– You can connect your VPC to both the Internet and your corporate datacenter and configure Amazon VPC route tables to direct all traffic to its proper destination.
  

Amazon VPC provides advanced security features such as security groups and network access control lists to enable inbound and outbound filtering at the instance level and subnet level. In addition, you can store data in Amazon S3 and restrict access so that it’s only accessible from instances in your VPC. Optionally, you can also choose to launch Dedicated Instances which run on hardware dedicated to a single customer for additional isolation.

You can create a VPC quickly and easily using the AWS Management Console. You can select one of the common network setups that best match your needs and press "Start VPC Wizard." Subnets, IP ranges, route tables, and security groups are automatically created for you, so you can concentrate on creating the applications to run in your VPC.

Amazon VPC provides all the same benefits as the rest of the AWS platform. You can instantly scale your resources up or down, select Amazon EC2 instances types and sizes that are right for your applications, and pay only for the resources you use - all within Amazon’s proven infrastructure.

You can host a basic web application, such as a blog or simple website in a VPC, and gain the additional layers of privacy and security afforded by Amazon VPC. You can help secure the website by creating security group rules which allow the webserver to respond to inbound HTTP and SSL requests from the Internet while simultaneously prohibiting the webserver from initiating outbound connections to the Internet. You can create a VPC that supports this use case by selecting "VPC with a Single Public Subnet Only" from the Amazon VPC console wizard.

You can use Amazon VPC to host multi-tier web applications and strictly enforce access and security restrictions between your webservers, application servers, and databases. You can launch webservers in a publicly accessible subnet and application servers and databases in non-publically accessible subnets. The application servers and databases can’t be directly accessed from the Internet, but they can still access the Internet via a NAT gateway to download patches, for example. You can control access between the servers and subnets using inbound and outbound packet filtering provided by network access control lists and security groups. To create a VPC that supports this use case, you can select "VPC with Public and Private Subnets" in the Amazon VPC console wizard.

You can create a VPC where instances in one subnet, such as webservers, communicate with the Internet while instances in another subnet, such as application servers, communicate with databases on your corporate network. An IPsec VPN connection between your VPC and your corporate network helps secure all communication between the application servers in the cloud and databases in your datacenter. Webservers and application servers in your VPC can leverage Amazon EC2 elasticity and Auto Scaling features to grow and shrink as needed. You can create a VPC to support this use case by selecting "VPC with Public and Private Subnets and Hardware VPN Access" in the Amazon VPC console wizard.

You can move corporate applications to the cloud, launch additional webservers, or add more compute capacity to your network by connecting your VPC to your corporate network. Because your VPC can be hosted behind your corporate firewall, you can seamlessly move your IT resources into the cloud without changing how your users access these applications. You can select "VPC with a Private Subnet Only and Hardware VPN Access" from the Amazon VPC console wizard to create a VPC that supports this use case.

You can periodically backup your mission critical data from your datacenter to a small number of Amazon EC2 instances with Amazon Elastic Block Store (EBS) volumes, or import your virtual machine images to Amazon EC2. In the event of a disaster in your own datacenter, you can quickly launch replacement compute capacity in AWS to ensure business continuity. When the disaster is over, you can send your mission critical data back to your datacenter and terminate the Amazon EC2 instances that you no longer need. By using Amazon VPC for disaster recovery, you can have all the benefits of a disaster recovery site at a fraction of the normal cost.