📅 Day 13 | AWS VPC — The Heart of AWS Networking 🌐
AWS VPC (Virtual Private Cloud) is the foundation of all networking inside AWS.
Every EC2 instance, database, load balancer, or container service you deploy lives inside a VPC.
Understanding VPC = understanding how your entire cloud infrastructure communicates.
🔥 Why VPC Is Essential
- 🛡️ Designing secure architectures
- 🌐 Creating public & private networks
- 🚀 Enabling internet access with Internet Gateway (IGW) & NAT Gateway
- 🔗 Connecting environments using VPC Peering
- ⚙️ Building scalable DevOps deployments
🎯 Why You Must Master VPC
Mastering VPC gives you full control over:
- Networking
- Security boundaries
- Traffic flow
- Service-to-service connectivity
VPC is one of the most criti
AWS VPC, Subnets, IGW, NAT, Peering, SSH...
✅ Quick Summary (What You’ll Get)
- Create VPCs (Mumbai & Delhi) + Subnets
- Attach Internet Gateway (IGW) + Public Route Table
- Create NAT Gateway + Private Route Table
- Create VPC Peering + routing both sides
- Delete resources in correct order
- PuTTYgen steps to convert PEM ↔ PPK
1) Create a VPC (Example)
| Step |
Action |
| Console |
VPC → Create VPC → VPC only
|
| Name |
MyVPC01 |
| IPv4 CIDR |
10.0.0.0/24 (or /16 for more IPs) |
| Result |
VPC created |
2) Create Subnets
Public Subnet (example)
| Field |
Value |
| VPC |
MyVPC01 |
| Name |
sub-public-1 |
| AZ |
ap-south-1a |
| CIDR |
10.0.0.0/28 |
| Auto-assign public IPv4 |
Enable |
Private Subnet (example)
| Field |
Value |
| VPC |
MyVPC01 |
| Name |
sub-private-1 |
| CIDR |
10.0.1.0/28 |
| Auto-assign public IPv4 |
Disable |
3) Internet Gateway (IGW) + Public Route Table
Internet Gateway
| Step |
Action |
| Create |
VPC → Internet Gateways → Create |
| Name |
igw-mumbai |
| Attach |
Attach to MyVPC01
|
Public Route Table
| Step |
Action |
| Create/Select |
Route tables → public-rt
|
| Add Route |
0.0.0.0/0 → Internet Gateway (igw-mumbai) |
| Associate |
Public Subnet (sub-public-1) |
4) NAT Gateway (Private → Outbound Internet)
| Step |
Action |
| Create |
NAT Gateway in public subnet (sub-public-1) |
| EIP |
Allocate new Elastic IP |
| Result |
NAT Gateway created |
Private Route Table
| Route |
Target |
0.0.0.0/0 |
NAT Gateway |
Associate this route table with the private subnet (sub-private-1).
Outcome:
Private EC2 → outbound internet OK, inbound blocked.
5) Security Groups (Recommended)
Public EC2 SG
| Rule |
Value |
| Inbound |
SSH (22) from your IP
|
| Inbound |
HTTP/HTTPS (80/443) from 0.0.0.0/0 (if web) |
| Outbound |
All allowed |
Private EC2 SG
| Rule |
Value |
| Inbound |
From Public EC2 SG or ALB |
| Outbound |
All allowed |
6) EC2 Deployment
Public EC2
- Launch into
sub-public-1
- Use Public-SG
- This can serve as a bastion/jump host
Private EC2
- Launch into
sub-private-1
- Use Private-SG
- SSH through bastion only
7) Create VPCs for Peering (Mumbai & Delhi)
Mumbai VPC
| Item |
Value |
| VPC Name |
vpc-mumbai |
| CIDR |
10.0.0.0/16 |
| Subnet |
sub1-mumbai → 10.0.0.0/28
|
| IGW |
igw-mumbai |
| Public RT |
Route → 0.0.0.0/0 → igw-mumbai
|
Delhi VPC
| Item |
Value |
| VPC Name |
vpc-delhi |
| CIDR |
172.16.0.0/16 |
| Subnet |
sub1-delhi → 172.16.0.0/28
|
| IGW |
igw-delhi |
| Public RT |
Route → 0.0.0.0/0 → igw-delhi
|
8) VPC Peering (Mumbai ↔ Delhi)
Create Peering
| Step |
Action |
| Create |
VPC → Peering Connections |
| Name |
my-peering |
| Requester |
vpc-mumbai |
| Accepter |
vpc-delhi |
Accept request from the Delhi side.
Add Routes (Both Sides)
Mumbai Route Table
| Destination |
Target |
172.16.0.0/16 |
Peering Connection |
Delhi Route Table
| Destination |
Target |
10.0.0.0/16 |
Peering Connection |
Security Groups
Allow from peer CIDRs if required.
9) Deletion / Cleanup Order
| Order |
Delete |
| 1 |
Peering connection |
| 2 |
EC2 Instances |
| 3 |
NAT Gateway (release EIP) |
| 4 |
Detach/Delete IGW |
| 5 |
Subnets |
| 6 |
Route Tables |
| 7 |
VPC |
This avoids “resource in use” errors.
10) AWS Limits & Quotas
| Resource |
Default Limit |
| VPCs per Region |
Usually 5 |
| Subnets |
Large (no issue normally) |
| NAT Gateways |
Limited by region, costly |
Request quota increase via AWS Service Quotas.
Thank You
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