Essential Cybersecurity Commands and Techniques for IT Professionals

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Introduction

Cybersecurity is a critical field requiring mastery of tools, commands, and best practices to protect systems from threats. This article covers verified Linux/Windows commands, cloud security configurations, and vulnerability mitigation techniques to enhance your defensive and offensive security skills.

Learning Objectives

  • Execute critical Linux/Windows commands for system hardening.
  • Configure cloud security policies (AWS/Azure) to prevent breaches.
  • Mitigate common vulnerabilities using command-line tools.

1. Linux System Hardening with `chmod` and `chown`

Command:

chmod 600 /etc/shadow 
chown root:root /etc/passwd

Step-by-Step Guide:

– `chmod 600` restricts read/write access to the `/etc/shadow` file (stores password hashes) to the root user only.
– `chown root:root` ensures the `/etc/passwd` file is owned by root, preventing unauthorized modifications.

2. Windows Firewall Rule for RDP Protection

Command:

New-NetFirewallRule -DisplayName "Block RDP Brute Force" -Direction Inbound -LocalPort 3389 -Protocol TCP -Action Block -RemoteAddress 192.168.1.100

Step-by-Step Guide:

  • Blocks inbound RDP (Remote Desktop Protocol) traffic from a specific IP (192.168.1.100) to prevent brute-force attacks.
  • Adjust `-RemoteAddress` to target suspicious IPs.

3. AWS S3 Bucket Hardening

Command:

aws s3api put-bucket-policy --bucket my-bucket --policy file://policy.json

Policy.json Example:

{
"Version": "2012-10-17",
"Statement": [{
"Effect": "Deny",
"Principal": "",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::my-bucket/",
"Condition": {"NotIpAddress": {"aws:SourceIp": ["192.0.2.0/24"]}}
}]
}

Step-by-Step Guide:

  • Restricts S3 bucket access to a specific IP range (192.0.2.0/24).

4. Detecting Open Ports with `nmap`

Command:

nmap -sV -p 1-65535 192.168.1.1

Step-by-Step Guide:

  • Scans all ports (-p 1-65535) on a target IP (192.168.1.1) and identifies services (-sV).
  • Use results to close unnecessary ports.

5. Mitigating SQL Injection with Input Sanitization

Code Snippet (PHP):

$user_input = mysqli_real_escape_string($conn, $_POST['input']);

Step-by-Step Guide:

  • Escapes special characters in user input to prevent SQL injection.
  • Always pair with prepared statements for full protection.

6. Azure API Security with JWT Validation

Command (Azure CLI):

az apim api update --name MyAPI --resource-group MyRG --set validateJwt=true

Step-by-Step Guide:

  • Enforces JWT token validation for Azure API Management endpoints.

7. Kali Linux Exploit Mitigation

Command:

sudo sysctl -w kernel.randomize_va_space=2

Step-by-Step Guide:

  • Enables ASLR (Address Space Layout Randomization) to hinder memory-based exploits.

What Undercode Say

  • Key Takeaway 1: Automation (e.g., AWS CLI, PowerShell) reduces human error in security configurations.
  • Key Takeaway 2: Proactive measures (firewall rules, input sanitization) are cheaper than breach remediation.

Analysis:

The rise of cloud and API-driven infrastructure demands granular access controls. Combining OS-level hardening (Linux/Windows) with cloud policies (AWS/Azure) creates a layered defense. Meanwhile, tools like `nmap` and ASLR mitigate exploitation risks. Future threats will target misconfigured IaC (Infrastructure as Code) templates, making automation audits essential.

Prediction:

By 2026, 70% of breaches will stem from misconfigured cloud permissions and API endpoints. Organizations must adopt Zero Trust frameworks and automate security compliance checks.

IT/Security Reporter URL:

Reported By: Aolamade889 Kpmg – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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