Tutorials System Design Tutorial
Networking Security in Distributed Platforms — Complete Guide
Networking Security in Distributed Platforms — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of System Design Tutorial on Toolliyo Academy.
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System Design Tutorial · Lesson 19 of 100
Networking Security in Distributed Platforms
Basics → Scale → Interview
Basics · 1 — Building blocks · ~6 min · Module 2: Networking and Traffic Management
What is this?
Network security limits who can talk to whom — private subnets, security groups/NACLs, WAF, zero-trust service identity.
Why should you care?
ShopNest databases must not be reachable from the public internet even if a password leaks.
See it live — copy this example
Sketch the architecture on paper. These lessons focus on concepts and trade-offs.
Public subnet: Gateway / CDN only
Private subnet: APIs, workers
Data subnet: Postgres, Redis (no inbound from Internet)
WAF: block SQLi patterns at edge
SG: API → DB on 5432 only from API SGRun Example »
This lesson uses terminal or setup steps. Run commands on your computer — the live editor appears on coding lessons.
What happened?
- Layered controls beat a single firewall rule.
- Least privilege security groups plus private data tiers shrink blast radius.
Practice next
- Draw public/private/data subnets for ShopNest.
- Allow DB ports only from app security groups.
- Put WAF in front of the public gateway.
- Add a bastion or SSM instead of open SSH.
- Deny cross-env (prod ← staging) traffic.
Remember
Private by default. Narrow security group rules. WAF + segmentation.
Locked data tier
ShopNest Postgres accepts connections only from API SG.
Outcome: Internet scanners never see the database port.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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