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45. Practice Exercises with Hints

45.4 Web Servers and MySQL – Build and Protect

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Apache/Nginx document root, nginx -t / apachectl configtest before reload. MySQL: keys, SQL_SAFE_UPDATES, never public RDS/3306.

Exercise Task Hint
E1 Change Nginx root to /var/www/sahyadri and test config before reload sudo nginx -t then sudo service nginx reload
E2 Create DB rajarani, table orders, insert 3 rows, SELECT with WHERE Primary key on id; never delete without WHERE in production habits
E3 Show why string-concat SQL in PHP is dangerous (write bad vs good sketch) Bad: "... WHERE id=$id"; good: prepared statements
E4 Explain DELETE vs TRUNCATE vs DROP in one line each Rows / empty table keep structure / remove table
E5 GRANT: create MySQL user zoya with SELECT-only on one DB Least privilege – app user ≠ root
Red team (attacker) does Blue team (defender) detects / stops
SQLi via ' OR '1'='1 on login (OWN DVWA) Prepared statements; input allow-lists; WAF as extra layer
Finds phpMyAdmin on public IP VPN / SSH tunnel; IP allow-list; disable when unused

Ravindra Bagale's Tip

Students connect the app as root. Interview: "app DB user = least privilege". That is gold. Don't worry – practise GRANT.

Lab

On OWN EC2 MySQL: create sahyadri DB, user appuser with password you set, GRANT SELECT,INSERT,UPDATE on that DB only. Login as appuser and prove DROP DATABASE fails. Screenshot.

Extended teaching notes

Why this lesson matters

Cameras, sensors and plant controllers often ship with weak defaults. Segment them from IT, change passwords, block inbound internet, and watch outbound traffic.

Real examples

Global: Mirai showed what default passwords on routers/cameras can do at scale. Indian SME (sample): a factory puts PLCs on a separate VLAN reachable only via a jump host.

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.

Extra depth

Re-read the original short section at the top of the page, then this expansion. Together they should exceed a solid lesson length. If anything still feels thin, add your own lab screenshot and a paragraph in your notebook — that personal evidence is what interviews ask for.

  • Permission before tools.
  • Patch and config before exploits.
  • Logs and backups before blame.
  • Teach one junior the warning from this page.