# AWS VPC
###### tags: `tutorials`

### Ref : https://www.youtube.com/watch?v=g2JOHLHh4rI
### IPv4 subnet creator : https://network00.com/NetworkTools/IPv4SubnetCreator/
### https://betterprogramming.pub/aws-console-creating-a-3-tier-architecture-f44e226e5842

## Questions
- Check route table - rotes

#### What is an IP Address?


#### Structure of an IPv4 Address
- IP Addresses are written in dotted decimal notation
- Each part of the address is a binary octet(Octet means we have 8 values)


## Networks and Hosts
- Every IP Address has `Network ID` and `Host ID`






#### Private IP ranges



## VPC Overview

A VPC is a logically isolated portion of the AWS cloud within a region.
We can create 5 VPC for a region by default, but we can request more

- A virtual private cloud (VPC) is a virtual network dedicated to your AWS account
- Analogous to having your own data center inside AWS
- It is logically isolated from other virtual networks in the AWS cloud
- Provides complete control over the virtual networking environment including selection of IP ranges,creation of subnets, and configuration of route tables and gateways
- You can launch your AWS resources, such as Amazon EC2 instances, into your VPC
- When you create a VPC, you must specify a range of IPv4 addresses for the VPC in the form of a Classless Inter-Domain Routing(CIDR) block, for example, 10.0.0.0/16
- A VPC spans all the availability zones in the region
- You have full control over who has access to the AWS resources inside you VPC
- By default you can create up to 5 VPCs per region
- A default VPC is created in each region with a subnet in each AZ

**Subnet** : A segment of a VPC's IP address range where you can place groups of isloated resources
**Internet Gateway/Egress-only internet gateway** : The amazon VPC side of a connection to the public internet for IPv4/IPv6
**Router** Routers interconnect subnets and direct traffic between internet gateways, virtual private gateways, NAT gateways, and subnets.
**Peering Connection** Direct connection between two VPCs
**VPC Endpoints** Private connection to public AWS services
**NAT Instance** Enables internet access for EC2 in private subnets (managed by you)
**NAT Gateway** Enables internet access for EC2 instances in private subnets(managed by AWS)
**Virtual Private Gateway** The amazon VPC side of a virtual private network(VPN) connection
**Customer Gateway** Customer side of a VPN connection
**AWS Director connect** High speed, high bandwidth, private network connection from customer to aws
**Security Group** Instance-level firewall
**Network ACL** Subnet-level firewall



#### Defining CIDR Blocks
**Rules and Guidelines**
- CIDR block size can be between /16 and /28 subnet mask
- The CIDR block must not overlap with any existing CIDR block thats associated with the VPC
- You cannot increase or decrease the size of an existing CIDR block
- The first four and last IP address are not avaialbe for use
- AWS recommend you use CIDR blocks from the RFC 1918 ranges:


#### Additional Considerations:
- Ensure you have enough networks and hosts
- Bigger CIDR blocks are typically better(more flexibility)
- Smaller subnets are OK for most use cases
- Consider deploying application tiers per subnet
- Split your HA resources across subnets in different AZs
- VPC peering requires non-overlapping CIDR blocks
- ==Avoid overlapping CIDR blocks== as much as posisble

#### Create a VPC
name : tpenmets-vpc
IPv4 CIDR block : 10.0.0.0/16

**Create public subnets**
Name: tpenmets-subnet-public-1A
AZ : us-east-1a
IPv4 CIDR block : 10.0.1.0/24

Name: tpenmets-subnet-public-1B
AZ : us-east-1b
IPv4 CIDR block : 10.0.2.0/24

Name: Name: tpenmets-subnet-private-1A
AZ : us-east-1a
IPv4 CIDR block : 10.0.3.0/24

Name: Name: Name: tpenmets-subnet-private-1B
AZ : us-east-1b
IPv4 CIDR block : 10.0.4.0/24

**Create private route table**
Name : tpenmets-private-RT
VPC: tpenmets-vpc
subnet associations: Priovate-1A, Private-1B

**Create Internet Gateway**
Name: tpenmetsIGW
VPC: tpenmets-vpc