AWS : VPC (Virtual Private Cloud) 2 - VPC Wizard

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Set Up the VPC and Internet Gateway

Let's create a VPC using the VPC Wizard in the VPC Console.

Select VPC with a Single Public Subnet:

Click Select.

The configuration page below displays the CIDR ranges that we'll use for our VPC and subnet (10.0.0.0/16 and 10.0.0.0/24, respectively), and the hardware tenancy setting. Enter a name for VPC - this helps us identify it in the VPC console after we've created it.

We can leave the rest of the default settings and then click Create VPC to create our VPC, Internet gateway, subnet, and route table.

When the work completes, a status window confirms that our VPC has been successfully created. Click OK to close the status window and return to the VPC dashboard.

Verify VPC's Components

We can use the default settings for the components that the VPC Wizard creates for us.

This section describes how we can view these components and their settings using a VPC console.

In the VPC navigation pane, click Your VPCs.

The console displays our default VPC (I deleted it) and the VPC that we just created.

Select the VPC that we just created (Default VPC is No since the VPC that we created is a nondefault VPC, therefore the Default VPC column displays No).

To see Internet Gateways, in the navigation pane, choose "Internet Gateways". We can find the Internet gateway that's attached to our VPC by looking at the VPC column, which displays the ID and the name (if applicable) of the VPC.

Each VPC has a set of DHCP options, a main route table, and default network ACL.

The VPC that we just created has two route tables:

The VPC came with a main route table by default
and the VPC Wizard created a custom route table in addition.

Our subnet is associated with the custom route table, which means that we use the routes in that table to determine how the traffic for the subnet flows. If we add a new subnet to our VPC, it uses the main route table by default.

custom route table:

The first row in the table is the local route, which enables instances within the VPC to communicate. This route is present in every route table by default, and we can't remove it.

The second row shows the route that the VPC wizard added to enable traffic destined for an IP address outside the VPC (0.0.0.0/0) to flow from the subnet to the Internet gateway. We refer to this subnet as a public subnet because all traffic from the subnet goes to the Internet gateway.

main route table:

The main route table has a local route, but no other routes. Therefore, any subnet we create is not exposed to the Internet initially, it's a private subnet. To expose a new subnet as a public subnet, we can either change the routing in the main route table, or associate the subnet with a custom route table.

Here is what we've done

Here is the VPC we created:

Created a VPC with a /16 CIDR block (a network with 65,536 private IP addresses).
Attached an Internet gateway to the VPC.
Created a size /24 subnet (a range of 256 private IP addresses) in the VPC.
Created a custom route table, and associates it with our subnet so that traffic can flow between the subnet and the Internet gateway.

Security group

Our VPC comes with a default security group.

Any instance not associated with another security group during launch is associated with the default security group. In this guide, we'll create a new security group, "WebServerSG", and specify this security group when we launch an instance into our VPC.

A security group acts as a virtual firewall to control the traffic for its associated instances. To use a security group, we add the inbound rules to control incoming traffic to the instance, and outbound rules to control the outgoing traffic from your instance. To associate a security group with an instance, we specify the security group when we launch the instance. If we add and remove rules from the security group, those changes will be applied to the instances associated with the security group automatically.

In the navigation pane, choose Security Groups, and then choose Create Security Group. In the Group name field, enter "WebServerSG" as the name of the security group, and provide a description.

On the Inbound Rules tab, we may choose Edit and add rules for inbound traffic, and then Save when we're done.

Launch an Instance into VPC

When we launch an EC2 instance into a VPC, we must specify the subnet in which to launch the instance. In this case, we'll launch an instance into the public subnet of the VPC we created. We'll use the Amazon EC2 launch wizard in the Amazon EC2 console to launch our instance.

Now, we have this:

Assign an Elastic IP Address to an Instance

In the previous step, we launched our instance into a public subnet - a subnet that has a route to an Internet gateway. However, the instance in our subnet also needs a public IP address to be able to communicate with the Internet. By default, an instance in a nondefault VPC is not assigned a public IP address.

For this, please check Step 4: Assign an Elastic IP Address to Your Instance.