36. Networking ‐ Create Hub VCN. Hub Public Subnet, Hub subnet‐Security list manually - SanjeevOCI/Ocidocs GitHub Wiki

Objective :-

1. Create a custom HUB VCN, with custom Public Subnet and custom security list.
2. Create a instance in the Custom VCN
3. Create Internet Gateway, Route Table & Route table to access the instance in the custom subnet.

Steps :-

1. Create HUB VCN

2. After a VCN is created, it has a default Route table & Default Security List

3. Now create a Public Subnet. Use Mtoolbox to calculate the Subnet CIDR

4. Create a New Security List. Also add Ingress/Egress rules in it

5. Add the new security list in the Public Subnet

6. Now remove the default security list

7. Create a New instance in the Custom VCN

8. Unable to reach the newly created bastion-server instance as there is no gateway to it

9. Let's create a gateway to access the bastion-server

10. Even after creating the Internet gateway, we are unable to access the bastion-server through putty. The reason being we have not created a route to the bastion-server

11. Go to HUB VCN --> Route Tables --> Create a custom Route Table. Do not touch the default Route Table

12. Now update the Default Route table in the Public Subnet with the custom Route Table

Now the Public Subnet is guided by the route defined in the Route Table - [HUB-VDN-PUBLIC-SUBNET-RT]

13. Our requirement is that instances in the Public Subnet should be able to connect to outside world. For this, we need to go to the Route Table - [HUB-VDN-PUBLIC-SUBNET-RT] and add a new route rule for the same

Now using this Internet Gateway, instances in the Public Subnet can connect to outside world

14. We are now able to access the bastion-server through putty

We have successfully created a custom HUB VCN, with custom Public Subnet and custom security list. Also created a new instance in the Custom VCN and made it accessible using Internet Gateway, Route Table & Route table