NAT overview

• NAT enables internet connectivity by address translations
  
• In AWS, to provide internet access to private subnets, we need to use NAT.
• There are two ways of using NAT in AWS
  • NAT instance:
    • An ec2 instance with NAT server in it
  • NAT Gateway:
    • NAT as a service by AWS
• NAT should be present in public subnet and router to the private subnets should have a route to the NAT and NAT should have a public ip (Elastic IP)
• Create a NAT Gateway
  
  
  
  
  
• Login into public ec2 and connect to private
  

Egress only Internet Gateway

• If all your subnets are private and if they need internet access, then we can use egress-only internet gateway
  

Multiple VPCs

• Consider a scenario where we create two vpcs in two regions
• The only way for establishing connection is using public ip address
  
  
• To solve these kind of issues we have vpn (Virtual Private Networks) to be very specific Site to Site VPN
• AWS has peering connection facility to connect vpcs.
• Rules for connecting are there should not be overlapping cidr ranges
• Peering Connections
  • Create a peering connection from any vpc to other
    
    
    
  • Accept the peering request
    
  • Now modify route tables to forward the request to pco when you have access other vpc’s cidr rnage
    
  • Do the same stuff in other region vpc