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10. MySQL Part 1: Install, Create, Insert and SELECT

10.1 Installing MySQL or MariaDB

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MariaDB he MySQL cha community fork aahe – aaplya kaamasathi purna compatible: tech mysql client, tech SQL, tech port 3306. Amazon Linux 2023 var MariaDB, Ubuntu var MySQL 8 vaparuya.

OS Package Service Admin login
Amazon Linux 2023 mariadb105-server mariadb sudo mysql
Ubuntu 22.04/24.04 mysql-server (MySQL 8.x) or mariadb-server mysql (or mariadb) sudo mysql (root uses auth_socket)
CentOS Stream 9 mariadb-server (or mysql-server for MySQL 8) mariadb (or mysqld) sudo mysql
Amazon Linux 2 (older) mariadb-server mariadb sudo mysql

Amazon Linux 2023

sudo yum install -y mariadb105-server
sudo service mariadb start
sudo systemctl enable mariadb
sudo service mariadb status

Ubuntu

sudo apt update
sudo apt install -y mysql-server
sudo service mysql start
sudo systemctl enable mysql
sudo service mysql status

sudo mysql_secure_installation      # remove anonymous users, test DB, remote root: answer Y
sudo mysql                          # log in as the admin (root) user

SELECT VERSION();
SHOW DATABASES;
EXIT;

Why this matters for security

A database should listen only on 127.0.0.1 (check sudo ss -tlnp | grep 3306) and port 3306 must never be open to the internet in the security group. Exposed databases with weak passwords are found by internet scanners and emptied or held for ransom.

Ravindra Bagale's Tip

Many students open port 3306 to "Anywhere" in the security group because they want to connect from their laptop with Workbench. Don't do that! Use an SSH tunnel: ssh -i key.pem -L 3307:127.0.0.1:3306 ec2-user@<IP> and give Workbench 127.0.0.1:3307. The port stays closed and the work gets done.

Practice task

Install the database on one instance, run mysql_secure_installation, log in with sudo mysql and print the version.

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.