LAB 6 ‐ RFC 1918(10.0.0.0 16,172.16.0.0 12, 192.168.0.0 16) - DevWithNehaCloud/Oracle-Cloud-Infrastructure-wiki GitHub Wiki

Networking (OCI)

Networking in Oracle Cloud Infrastructure (OCI) refers to the setup and management of virtual networks that enable communication between cloud resources, the internet, and on-premise systems in a secure and controlled manner.

It is built around the Virtual Cloud Network (VCN), which acts as a private, customizable network where you define IP ranges, subnets, routing rules, and security policies.

🔑 Public IP vs Private IP

🔹 Public IP Address

A Public IP is an internet-accessible IP address assigned to a resource.

Reachable from the internet
Used for web servers, load balancers, or bastion hosts
Requires an Internet Gateway for connectivity
Example: Accessing a website hosted on OCI
We can check our public IP address by clicking the url https://whatismyipaddress.com/

🔹 Private IP Address

A Private IP is an internal IP address used within a VCN.

Not accessible directly from the internet
Used for internal communication (app servers, databases)
More secure by default
Can access the internet via NAT Gateway (outbound only)

Public vs. Private IP Comparison

Feature	Public IP	Private IP
Access Scope	Accessible from the Internet	Accessible only within VCN/VPN
Security Profile	Lower (Needs strict Security Lists/NSG)	Higher by default (Isolated)
Primary Usage	Frontend, Web Servers, Load Balancers	Backend, Databases, Microservices
Internet Access	Direct via Internet Gateway (IGW)	Outbound only via NAT Gateway
Communication	VCN to External Networks	Internal (Intra-VCN) communication

IANA & RFC 1918 Overview

What is IANA?

The Internet Assigned Numbers Authority (IANA) is the global entity responsible for managing IP addresses, domain names (DNS), and protocol parameters. It ensures that no two organizations use the same public IP address globally.

What is RFC 1918?

RFC 1918 is the technical memorandum that established the standards for Private IP Addressing. These addresses are reserved for internal networks (like an OCI VCN) and are not routable on the public internet.

Note:-Public IP addresses are limited and expensive. To optimize costs and security, we use private IP ranges as defined by RFC 1918, ensuring that internal application traffic remains free and isolated from the public internet.

Key Benefits of Private IP Addressing (RFC 1918)

Benefit	Description
Security	Not reachable from the internet; provides an inherent layer of isolation.
Cost	Completely free to use; no registration or licensing fees required.
Conservation	Prevents the exhaustion of Public IPv4 addresses.
Scalability	Allows for large-scale internal networking with millions of available IPs.

Pro-Tip for OCI: Always place your sensitive workloads (Database, Backend) in a Private Subnet using RFC 1918 ranges to ensure they are never exposed to the public web.