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4. Amazon EC2: Launch and Connect to Your Linux Server

4.2 Choosing an Instance Type

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Instance type mhanje hardware chi size – vCPU, RAM aani network. Labs sathi chhota burstable type (t3.micro, t2.micro) purto. Naav kasa vachaycha te khali bagha.

      t  3  a  .  micro
      │  │  │     └── size: nano, micro, small, medium, large, xlarge, 2xlarge ...
      │  │  └──────── extra attribute: a = AMD, g = Graviton (ARM), i = Intel, d = local NVMe, n = network
      │  └─────────── generation (higher = newer, better price/performance)
      └────────────── family: t = burstable general purpose
Family Category Use case Examples
T General purpose, burstable (CPU credits) Dev/test, small websites, labs t3.micro, t3.small, t4g.small
M General purpose, balanced App servers, small databases m7i.large, m7g.large
C Compute optimised Batch processing, gaming, high-traffic web c7i.xlarge
R / X Memory optimised Large databases, in-memory caches r7i.large
I / D Storage optimised NoSQL, data warehouses i4i.large
P / G / Inf / Trn Accelerated (GPU/ML chips) Machine learning, video g5.xlarge

Free tier

AWS offers a free tier or free credits for new accounts, and the offer changes over time. Look for the "Free tier eligible" label in the console and check the official AWS free tier page. The AWS UI may vary slightly from the screenshots and steps in any book.

Ravindra Bagale's Tip

If you choose a Graviton (t4g) type but keep an x86 AMI, the launch fails – many students get stuck here. The architecture of the type and the AMI (x86_64 or arm64) must match. If in doubt, use t3.micro + 64-bit (x86) for labs.

Practice task

Decode these names: t3.micro, t4g.small, m7i.large, c7i.xlarge, r7i.large. For each, write the family, generation, attribute and size.

Extended teaching notes

Why this lesson matters

Use this lesson to strengthen systems you own: understand the risk, practise safely in a lab, then write and apply the fix.

Apply the fix across stacks

Same class of bug, same idea in every language.

Java / Spring Boot

Parameterise queries, encode output, CSRF tokens, limited Actuator, dependency scanning.

ASP.NET Core

EF Core / parameterised SQL, Razor encoding, HTTPS, Data Protection.

Node.js / Express

helmet, parameterised SQL, npm audit, avoid eval and shell concat.

Python / Django / Flask / FastAPI

ORM, autoescape, pip-audit, Bandit; never shell=True with user input.

PHP / Laravel

PDO/Eloquent, Blade escaping, composer audit.

Go / Ruby

database/sql placeholders / ActiveRecord; html/template / ERB escaping; govulncheck / Brakeman.

nginx / Apache / Tomcat

Hide versions, TLS, security headers, least-open ports.

MySQL / PostgreSQL / MongoDB / Redis

Private networks, auth on, least-privilege users, no 0.0.0.0/0.

AWS / Azure / GCP

Roles not long-lived keys, private data stores, cloud audit logs on.

Mini case study

Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.

Defender's worksheet (do this today)

  1. Write the lesson title, date and the exact lab target you are allowed to use.
  2. List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
  3. Run one safe check from the lesson on a lab system only. Paste the command and output.
  4. Write a two-sentence fix you would give a teammate.
  5. Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.

Indian workplace (sample data)

Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).

Global practice

Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.

Everyday analogy

Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.

Key terms

  • Control: a safeguard (patch, config, process, detection).
  • Finding: a weakness backed by evidence.
  • Remediation: the fix plus how you verified it.
  • Scope: systems you have written permission to touch.
  • Least privilege: only the access the task needs.
  • Defence in depth: several layers so one failure does not end the story.

Common mistakes

  • Skipping written permission "just for a quick scan".
  • Practising on hostel, office or public targets without authorisation.
  • Collecting tool output without writing the fix.
  • Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
  • Publishing screenshots that contain secrets, cookies or internal hostnames.

Recap

  • Evidence, fix, owner, date.
  • Own lab only.
  • Fix > spectacle.