Services Covered

  • EC2 EC2
  • VPC VPC

Lab description

In this lab I will create a new VPC with a private and public subnets. Then I will launch a host bastion in public subnet and another instance in the private one. Both subnets will have route table associated with them. Instance on hte public subnet route will have internet access through the internet gateway. The instance in private subnet will have inbound internet traffic through the NAT device. In addition to security groups, the private subnet also has a network access control list (NACL) as an added measure of security.


Learning Objectives

  • Create VPC
  • Create a subnets and an internet gateway
  • Configure routing for your VPC using a route table
  • Create and manage an EC2 instance and an associated Elastic IP Address (EIP) within your VPC
  • Create NACL and NAT Gateway

Lab date

04-11-2021


Prerequisites

  • AWS account
  • PuTTY for SSH connection

Lab steps

  1. Create a VPC with CIDR block: 10.0.0.0/16 and default tenancy.
  2. Navigate to Internet Gateways and create a new one. Then attach it to the VPC from previous step.
  3. Next create a Subnet in your VPC. This one will be public so give it an adequate name. Choose one AZ and provide CIDR block: 10.0.20.0/24.
  4. Go to Route Tables and create a new one in your VPC. When created click on Edit routes and add route: Destination: Enter 0.0.0.0/0 and as target choose the earlier created Internet Gateway.
  5. Navigate back to Subnets and choose the public one created in previous step. Then click the Route table tab then Edit route table association and as Route table ID choose the one created in step 4.
  6. Create a basion host by creating a EC2 Linux instance. In Instance Details tab for Network choose the VPC created in first step, as subnet the public one from step 2 and Enable Auto-assign Public IP. Create a new security group that will allow SSH inbound and as source: MyIP.
  7. Now create a private Subnet. Go to VPC dashboard and create a subnet within your VPC, give it a name indicating that it’ll be a private one, choose an AZ and as CIDR block enter 10.0.10.0/24.
  8. Then create a Route table in your VPC. Next edit routes and add a route with destination 0.0.0.0/0 and target the Internet Gateway from step 2. This is a temporary target value. Later in this lab, you will add a NAT device (gateway or instance) and update the Target for the PrivateRouteTable to the NAT device. Now you should have two subnets one called Private and one Public:

    Choose the Private one and Edit route table association by changing the Route table ID to the one created earlier in this step
  9. Create a Network Access Control List for your private subnet. Navigate to Networks ACLs and create a new one with name indicating that it’ll be for a private subnet. When created go to Subnet associations and associate it with the private subnet
  10. Create inbound and outbound rules for your private Network Access Control List (NACL). Select it and go to Inbound rules tab and then edit. Add two new rules as pictured under

    Then edit outbound rules as follows:

  11. Launch an instance in a private subnet created earlier, that would match a database instance in real life deployment. In EC2 Dashboard launch a new instance in your VPC ans select Private subnet, no need for public IP. Create a Security group that will allow inbound SSH request from bastion host only. As a source of SSH choose the Custom and bastions security group.

    You should have two instances, you might change their names for clarity:

  12. Go to Security groups tab and choose the bastions SG. Edit it outbound rule and restrict it to the private SG for SSH.
  13. Connect to your bastion instance using for example PuTTY and Pageant and remember to check Allow agent forwarding in order to be able to connect to the private instance.

    When connected to bastion host use SSH to connect to the private instance.

    Now you should be in in the private instance, but if try to run

    sudo yum update

    The instance won’t be able to access the internet.

  14. In this lab step, you will create a NAT Gateway that will be used by the EC2 instance in your private subnet to access the public internet. Navigate to VPC click NAT Gateways and create a new one. As subnet choose the Public one and Connectivity type: Ensure Public is selected. Then allocate Elastic IP.

    When NAT Gateway’s state becomes available go to Route Tables select the one for private subnet end edit routes. Change the one with destination set to 0.0.0.0/0 to have NAT Gateway as target

  15. Now if you try to run yum update on your private instance it should have internet connection


Lab files


Acknowledgements

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