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Security Infrastructure

Secure 3-Tier Web Application Infrastructure

Built a fortress-like 3-tier network architecture with Web, App and DB tiers in isolated private subnets, AWS WAF, hardened Bastion and strict NACLs/Security Groups.

Industry: Web Application Platform
Duration: 3 Weeks
Role: Security Infrastructure Architect
Status: Live in Production
Zero
Public DB Access
WAF
DDoS Protection Enabled
3-Tier
Isolated Network Architecture
Bastion
Hardened Access Control
The Challenge

Where It Started

Built a fortress-like 3-tier network architecture with Web, App and DB tiers in isolated private subnets, AWS WAF, hardened Bastion and strict NACLs/Security Groups.

Problems
  • Database directly reachable from public internet
  • No WAF — exposed to common web application attacks
  • Single flat network — no tier separation or isolation
  • Admin access via direct SSH to production servers
Our Solution
  • 3-tier architecture isolating Web, App and DB layers
  • AWS WAF + Shield for DDoS and OWASP Top 10 protection
  • Hardened Bastion host as the single admin entry point
  • Layered NACLs and Security Groups for defense in depth
Architecture

System Overview

Internet User AWS WAF DDoS Shield AWS VPC — 3 Tier Architecture Web Tier Nginx + LB (Public) App Tier Private Subnet Security Controls NACLs & Security Groups Private Subnets Bastion Host Access Zero Public DB Access WAF + DDoS Protection DB in isolated private subnet — zero direct internet access
Implementation

How We Delivered It

Week 1
Network Architecture Redesign
Designed the 3-tier VPC with fully isolated Web, App and Database subnets and layered security controls.
Week 2
WAF, Bastion & NACLs
Deployed AWS WAF rules, hardened the Bastion host with key-only SSH, and configured NACLs plus Security Groups.
Week 3
Nginx & Handover
Configured Nginx for TLS termination and reverse proxying, validated the full security posture, and handed over.
Tech Stack

Technologies Used

AWS VPCPrivate SubnetsAWS WAFNginxBastion HostNACLsSecurity Groups
Results

The Impact We Delivered

0
Public DB Access
Database tier is completely unreachable from the public internet.
Active
WAF + DDoS Shield
AWS WAF and Shield actively block malicious traffic in real time.
3-Tier
Network Isolation
Web, App and DB tiers each run in independently secured subnets.
Hardened
Bastion Access Control
All admin access is funneled through a single hardened entry point.
"Our previous setup was a flat, exposed network. eMergence rebuilt it into a proper defense-in-depth architecture — it feels like a completely different, much safer platform."
— CTO, Web Application Platform (Client, Confidential)

Project Details

IndustryWeb Application Platform
Duration3 Weeks
Team Size2 Engineers
RoleSecurity Infrastructure Architect
StatusLive in Production

Services Used

AWS VPCWAFPrivate SubnetsNginxBastion HostNACLs
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Key Wins

  • Zero public database access
  • Full 3-tier network isolation
  • AWS WAF + Shield DDoS protection
  • Hardened single-entry Bastion access
  • Layered NACLs & Security Groups

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