After diving deep into advanced networking diagnostics on Day 17, Day 18 of my Linux learning journey focused on network routing, security controls, service scanning, and real-world API interaction.
These tools are not just “commands” — they are core building blocks used daily by Linux administrators, Cloud engineers, DevOps teams, and SREs to inspect traffic, secure systems, automate checks, and debug APIs.
Today’s learning felt extremely production-oriented.
🔹 What I Learned & Practiced
Today, I explored and practiced the following Linux commands:
- route
- nmap
- wget
- watch
- iptables
- curl
- jq
Each tool plays a critical role in network visibility, security, automation, and troubleshooting.
🔹 route – Viewing & Managing Network Routes
The route command displays the system’s routing table and helps understand how packets leave the system.
Example:
- route -n
✔️ What it does:
- Shows default gateway
- Displays network paths
- Helps understand packet forwarding
Use case:
Diagnosing internet connectivity issues and verifying correct gateway configuration in servers and cloud VMs.
🔹 nmap – Network Scanning & Security Auditing Tool
nmap is a powerful tool for network discovery and port scanning.
Example:
- nmap localhost
✔️ Key learnings:
- Detects open ports
- Identifies running services
- Helps assess attack surface
Use case:
Used by DevOps, SysAdmins, and Security teams to verify exposed services and perform basic security audits.
🔹 wget – Non-Interactive File Download Tool
wget is commonly used for downloading files from the web or APIs directly from the terminal.
Example:
- wget https://example.com/file.zip
✔️ Why it matters:
- Automates downloads in scripts
- Works without a GUI
- Supports resume and background downloads Use case: Downloading application packages, logs, backups, or artifacts in CI/CD pipelines.
- 🔹 watch – Real-Time Command Monitoring
watch repeatedly runs a command and displays the output in real time.
Example:
- watch -n 2 ss -tulnp
✔️ Use cases:
- Monitor port usage
- Track system or network changes
- Observe real-time updates during troubleshooting This is extremely useful during incident debugging.
🔹 iptables – Linux Firewall & Traffic Control
iptables is the backbone of Linux firewall rules.
Example:
- iptables -L
✔️ What it controls:
- Incoming and outgoing traffic
- Port-level access
- Network security policies
Use case:
Securing servers by allowing only required ports (e.g., 22, 80, 443) and blocking unwanted traffic.
🔹 curl – API & HTTP Request Testing Tool
curl is essential for testing APIs, web services, and endpoints.
Example:
- curl https://api.github.com
✔️ Key learnings:
- Supports GET, POST, PUT, DELETE
- Works with headers, tokens, and payloads
- Critical for API debugging
Use case:
Used heavily in DevOps pipelines, microservices testing, and cloud application debugging.
🔹 jq – JSON Parsing & Formatting Tool
jq is used to parse and manipulate JSON data from APIs.
Example:
- curl https://api.github.com | jq
✔️ Why it’s powerful:
- Formats raw JSON
- Extracts specific fields
- Makes API responses readable
Use case:
Analyzing API responses in automation scripts and debugging cloud services.
🔹 Why These Commands Matter in Real-World Systems
These tools are critical because:
- Routing defines how traffic flows
- Open ports define security risk
- Firewalls control attack surfaces
- APIs power modern cloud applications
- Automation depends on CLI-based tools
- Real-time monitoring reduces downtime
Together, these commands bridge the gap between Linux basics and real production systems.
🚀 Day 18 Takeaway
Day 18 significantly strengthened my understanding of:
- Network routing and gateways
- Port scanning and security awareness
- Firewall fundamentals
- API testing and JSON parsing
- Real-time system monitoring
- Automation-friendly CLI tooling
Linux networking is not just about connectivity anymore —
it’s about security, observability, automation, and control.
Step by step, Linux is becoming less intimidating and more empowering.
Consistency remains the real superpower 🔑💪
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