AWS Networking with Virtual Private Cloud for Beginners

Now that we understand what is a Virtual Private Cloud and the role of IP addresses, let’s get into a feature of VPC called subnets. If you think of VPC as a network of computers, then a subnet is a smaller group of computers organized within a VPC. Recall that a VPC is defined by a range of IP addresses specified in a CIDR notation. So it makes sense that a subnet within a VPC would be made up of a subset of IP addresses of the VPC. So, a subnet is defined as a sunset of ip addresses within a VPC.

In this lesson, we’ll discuss what is an Internet Gateway and why we need it in a virtual private cloud. We’ll also discuss a process known as network address translation or NAT.

In this lesson, we’ll look at what is an elastic IP Address. Simply, an Elastic IP address is just another word for the public IP address we’ve been talking about. So, an elastic IP address is one of the 4.3 billion public IP addresses used on the public internet. Recall in our previous lesson that there are governing bodies who allocate these IP addresses and one of their jobs is to make sure there is no duplicate allocation. So you might be asking, do we need to go to these folks everytime we need a public ip address? The answer is no. It turns out that AWS already got a large allocation of public IP addresses for each region.

In this lesson, we’ll discuss what is an Elastic Network Interface or ENI. If you ever took apart a computer, you may have seen a network card with a jack for network cable. In these types of computers, you can change the network card or take it out and put it on another computer. Well, an elastic network interface is kinda like these network cards except they are virtual components we can use to assemble our EC2 server. In AWS, one of the main functions of an elastic network interface is to associate private and public IP addresses

In this lesson, we’ll discuss what is a route table and what it’s used for.  How does a router know where to direct the packets so it ends up where it needs to go? At a high level, a router has a kind of a look up table and in AWS, this is called a route table.  Each entry in the route table is called a route. Whenever a router receives a packet, it looks at the packet’s destination IP address then compares a route table. Then when a matching destination is found, the router forwards the packet to the corresponding target.

In this lesson, we’ll discuss what is a security group and its purpose. If you’ve been following the lessons so far, we’ve already come across security groups several times already but we just selected the default option without understanding what it means. At a high level, a security group is a feature that allows us to control the inbound and outbound traffic at the EC2 instance level. This is sometimes referred to as a firewall.

In this lesson, we’ll discuss what is a “NAT Gateway” and one of its common use cases. We already saw a simple version of Network Address Translation in the Internet Gateway lesson where the internet gateway flipped the private and public IP address when traffic leaves the VPC to the public Internet. The NAT Gateway is a more scalable version of this idea.

In this lesson, we’ll discuss what is a VPC peering and look in depth at how VPC peering works. At a high level, the VPC peering is a way to connect 2 VPC’s such that resources in each VPC’s can connect to each other using their private IP address. This allows the traffic to stay within the AWS infrastructure and never traverse the public internet thus reducing potential threats from the outside. The VPC’s can be in the same account or different accounts. The VPC’s can even be in different regions.

Congratulations. You have successfully completed the AWS Networking with Virtual Private Cloud course.  Before wrapping up, there are 4 recommended next steps. 

1. VPC Limitation

2. VPC Pricing

3. Security

4. Automation

Thank you and I would appreciate if you leave a rating and comment to help me improve on future courses.  Keep learning & keep building.