Ever wonder how your entire house or office gets by on a single public IP? It’s NAT, and specifically PAT (Port Address Translation). I just built this from scratch in Cisco Packet Tracer to see exactly how it works under the hood.

The Topology:

PC0 & PC1 > Switch > R1 (NAT) > R2 (ISP) > Server

What I configured:

- Interface IPs and descriptions (LAN: 192.168.10.0/24, Outside link: 203.0.113.0/30)

- Tagged interfaces: `ip nat inside` on the LAN side, `ip nat outside` on the ISP side

- Default route (`0.0.0.0/0`) pointing to the ISP router

- Standard ACL to define allowed internal hosts, tied to: `ip nat inside source list 1 interface gig0/1 overload`

- Saved it all with `copy running-config startup-config`

Verification:

- Successfully pinged the ISP server from the internal PCs.

- Ran `show ip nat translations` to watch it work. Seeing the unique port numbers map to the single public IP is where the concept really clicks.

The Takeaway:

NAT gets private addresses to the internet. PAT takes it a step further by using unique source port numbers to track each individual session, allowing hundreds of devices to share one public IP without traffic collisions.

Lab is configured, tested, and working. On to the next one.

*Note:* If you’re currently studying for your CCNA or just building your network engineering fundamentals, I’ve been working through the Network Engineer Complete Bundle (L1 to L3) from CodeLivly. It covers this exact type of architecture from the ground up without the usual textbook fluff. It’s a solid resource if you want structured, practical labs:

https://resources.codelivly.com/product/network-engineer-complete-bundle-l1-l2-l3-foundations-to-advanced-architecture/

They fail because they don’t know what to do when the alert actually appears.

You open the SIEM.

There are dozens of alerts.

Which one matters?

What do you check first?

Is it a false positive?

Do you investigate the user, host, IP, process, or all of them?

When should you contain the threat?

When should you escalate?

That workflow is what separates someone who has watched a few SOC videos from someone who can actually work an incident.

We put together this SOC Cheat Sheet as a simple reference for the things analysts use constantly.

Alert triage, log sources, severity levels, investigation steps, response actions, IOCs, TTPs, escalation, and the full SOC workflow from detection to reporting.

But a cheat sheet is only the starting point.

If your goal is to move into cybersecurity and eventually work as a SOC Analyst, focus less on collecting random certificates and more on learning how to investigate real activity, understand logs, make decisions, and explain what happened.

That is exactly what we built into the SOC Analyst Complete L1 + L2 + L3 Bundle.

It is designed to take you from the fundamentals into deeper SOC investigation, detection, incident response, and practical analyst skills.

If SOC is the career path you are serious about, start here:

https://resources.codelivly.com/product/soc-analyst-the-complete-l1-l2-l3/

Learn the process. Practice the investigation. Build the skills employers expect.

If you’re serious about building a career in cybersecurity, watching random tutorials only gets you so far.

At Codelivly, we’re starting an 8-week Ethical Hacking & Penetration Testing Live Training program designed for people who want practical skills they can actually build on for roles like junior pentester, security analyst, web security tester, or offensive security engineer.

The training is live and hands-on. We’ll cover reconnaissance, Nmap, enumeration, vulnerability discovery, Linux and Windows privilege escalation, Burp Suite, web application testing, SQL injection, XSS, IDOR, API security, JWT testing, exploitation, and reporting.

You’ll also work through practical labs so you understand the process, not just the commands.

24 live classes · Monday / Wednesday / Friday · 4:45 PM UTC
Led by Rocky, Founder of Codelivly

If cybersecurity is the career you want to move into, this is built to give you a structured starting point and the practical foundation to keep progressing.

More details and enrolment:
https://training.codelivly.com/programs/ethical-hacking-and-penetration-testing

Hey everyone,

I made a simple Nmap cheatsheet for anyone learning host discovery, port scanning, service detection, NSE scripts, output options, and common commands. I wanted to keep it clear, practical, and easy to use without unnecessary fluff.

If you want to go beyond the cheatsheet, I’m also sharing these free Nmap learning resources:

Free Room:
https://codelivly.com/rooms/nmap-fundamentals

Free Video:
https://www.youtube.com/watch?v=IMzRT_A60r4

This is useful if you’re a:

• beginner in cybersecurity
• student learning networking or pentesting
• someone revising Nmap basics
• lab/CTF learner who wants a quick reference

If you want, I can also post more simple cybersecurity cheatsheets like:

• Linux basics
• Burp Suite
• Web app testing
• Enumeration
• Privilege escalation

Would love your feedback.

I put together a practical guide around an SRWE Final Packet Tracer Skills Assessment for anyone learning networking and wanting something more hands-on than just reading theory.

The PDF walks through a network with 1 router and 2 switches and covers:

• VLANs and trunking
• Native VLAN configuration
• EtherChannel with LACP
• Port security
• SSH and basic device hardening
• Router subinterfaces
• IPv4 and IPv6 dual-stack configuration
• DHCP pools
• Switch management SVIs
• Default routes and Loopback interfaces
• Packet Tracer verification commands
• Common configuration errors and troubleshooting

It also goes through actual issues you can run into in Packet Tracer, such as native VLAN mismatches, LACP suspension, STP blocking, incomplete commands, and misspelled IOS commands, rather than only showing the final configuration.

There are also verification commands at the end for checking EtherChannel, trunking, spanning tree, port security, DHCP, routing, and SSH.

📘 CCNA Practical: The Hands-On Network Engineer Guide
https://resources.codelivly.com/product/ccna-practical-the-hands-on-network-engineer-guide/

📗 Computer Networking All-in-One For Dummies
https://resources.codelivly.com/product/computer-networking-all-in-one-for-dummies/

If you're learning networking, CCNA, or working through Packet Tracer labs, hopefully these are useful.

Codelivly community:
https://t.me/codelivly

Free malware analysis, reverse engineering and exploit development resources

If you're learning malware analysis, reverse engineering, or exploit development, there are a lot of genuinely good free resources available.

Here’s a list worth bookmarking:

🔴 Malware & Reverse Engineering

• Exploit Reversing — 700+ pages of malware analysis and exploit research
https://exploitreversing.com

• Malware Unicorn — RE101, RE102, macOS reverse engineering and PE injection
https://malwareunicorn.org

• Malware Research / University Course — Full malware analysis course
https://class.malware.re

• Azeria Labs — ARM assembly, shellcode and heap exploitation
https://azeria-labs.com

• revers.engineering — Applied reverse engineering and hypervisor development
https://revers.engineering

🔴 Binary & Kernel Exploitation

• pwn.college — From buffer overflows to kernel exploitation
https://pwn.college

• P.Ost2 — 30+ courses covering WinDbg, IDA, Ghidra, UEFI and kernel exploitation
https://p.ost2.fyi

• Corelan — Exploit development tutorials covering years of research
https://corelan.be

• Windows Internals — Windows internals, secure kernel, VBS, KDP and dynamic analysis
https://windows-internals.com

For beginners

If you're completely new to malware analysis, I also put together a beginner-focused book covering the fundamentals, lab setup, static/dynamic analysis and practical concepts:

📘 Malware Analysis for Beginners
https://resources.codelivly.com/product/malware-analysis-for-beginners/

And for a more structured learning path:

https://codelivly.com/career-paths/malware-analyst

Save these somewhere. There’s enough material here to keep you busy for a long time.

What other free malware/reversing resources would you add to this list?

If you’re interested in digital forensics / DFIR and want something more structured than jumping between random tutorials, Codelivly has a free Digital Forensics career path.

It covers things like:

• File systems and evidence handling
• Disk forensics
• Memory forensics
• Network forensics
• Log analysis and timeline reconstruction
• Malware analysis
• Chain of custody
• Digital investigation

The path includes 18 learning paths and practical work with tools like Autopsy, FTK Imager, Volatility, and Wireshark. You can work through it at your own pace and track your progress as you go.

It's completely free to study:

https://codelivly.com/career-paths/digital-forensics

There’s also a Discord community if you want to discuss cybersecurity, labs, or learning with other people:

https://discord.gg/RTZyZXATE

If you're learning DFIR right now, would be interested to hear what you're working on.

Finished a small office network simulation in Cisco Packet Tracer.

The topology includes:

• 1 Router
• 1 Switch
• 3 PCs
• 3 Network Printers
• 3 CCTV Cameras
• 1 Server

The main focus was getting the network configured and everything communicating properly.

What was done:

• Designed the network topology
• Assigned IPv4 addresses and subnet masks
• Configured the router and switch
• Configured default gateways
• Connected all end devices
• Tested connectivity with ping
• Troubleshot basic connectivity issues

It was a simple setup, but good practice for understanding how the different devices fit together in an actual LAN.

Working on projects like this makes concepts such as IP addressing, switching, routing, and troubleshooting much easier to understand than just reading about them.

Tools: Cisco Packet Tracer, IPv4, Router, Switch, LAN

For anyone practicing CCNA/networking, this hands-on guide also has Packet Tracer labs, subnetting exercises, switching, routing, and troubleshooting:

CCNA Practical: The Hands-On Network Engineer Guide

Every device you connect gets an IP address without you typing anything. Ever wondered how?

That's DHCP, and I just built it.

The goal: set up a DHCP server so both wired and wireless devices receive their network settings automatically, with zero manual configuration on any client.

Network Configuration
DHCP Server IP: 192. 168. 1. 10
Default Gateway: 192. 168. 1. 1
DHCP Pool Starts At: 192. 168. 1. 50
Wired + Wireless Clients: DHCP

You type “Hello”, hit send, and it looks instant.

But behind that one message, the data goes through several layers before it reaches the other device.

This is encapsulation:

Data → Segment → Packet → Frame → Bits

At the sender:

• Layer 7 – Application: The app creates the data.
• Layer 6 – Presentation: Data can be formatted, compressed, or encrypted.
• Layer 5 – Session: The communication session is managed.
• Layer 4 – Transport: TCP/UDP and port information are added.
• Layer 3 – Network: Source and destination IP addresses are added.
• Layer 2 – Data Link: MAC addresses and frame information are added.
• Layer 1 – Physical: Everything becomes bits/signals traveling through the network.

At the other end, the process happens in reverse:

Bits → Frame → Packet → Segment → Data

That's decapsulation.

Once you understand this, troubleshooting becomes much easier. Instead of thinking “the network isn't working”, you can start asking:

Is it the application?
The port?
The IP/routing?
The MAC/VLAN?
Or the physical connection?

I put together this diagram as a quick reference while studying networking. Thought it might be useful for anyone working through CCNA, Network+ or general networking fundamentals.

And if you're currently learning networking, having something more structured than random tutorials helped me a lot. These are a few resources worth keeping around depending on where you're at:

📘 Complete L1 → L2 → L3 Network Engineer bundle — useful if you want everything in one place:
Network Engineer Complete Bundle L1–L3

📗 Computer Networking All-in-One — a broader reference for networking fundamentals:
Computer Networking All-in-One for Dummies

📕 CCNA Practical — more focused on the hands-on side of networking and Cisco concepts:
CCNA Practical: The Hands-On Network Engineer Guide

Honestly, I'd rather have one solid reference open while doing labs than keep jumping between 15 browser tabs. 😅

What part of the OSI model took you the longest to understand?

Starting with the basics before getting into routing, switching, troubleshooting, and network security.

Day 1 covers the core networking concepts and OSI model that are worth understanding properly before moving into more advanced topics.

For anyone learning networking, I’ve also put together some resources:

Network Engineer L1 – The Complete Beginner’s Guide to Networking, Subnetting, Troubleshooting & Cisco CLI Fundamentals
Network Engineer L1

Network Engineer L2 – Advanced Enterprise Networking, Routing, Switching, Security & Automation
Network Engineer L2

Network Engineer L3 – Advanced BGP, Data Center, Cloud & Security Architecture
Network Engineer L3

Network Engineer Complete Bundle – L1, L2 & L3
Complete Network Engineer Bundle

Join the community:
Discord: Codelivly Discord

TCP 3-Way Handshake — SYN → SYN-ACK → ACK

One of those networking concepts that sounds more complicated than it actually is.

Before a TCP connection starts sending application data, the two endpoints perform a 3-way handshake:

1. SYN
Client → Server
“I want to establish a TCP connection. Here’s my initial sequence number.”

2. SYN-ACK
Server → Client
“I received your SYN, and here’s my own sequence number.”

3. ACK
Client → Server
“Got it. We’re synchronized.”

The connection then moves into the ESTABLISHED state and data transmission can begin.

A simple way to remember it:

SYN → SYN-ACK → ACK → ESTABLISHED

The interesting part is that the handshake isn't just a formality. TCP uses sequence and acknowledgment numbers to synchronize both sides and establish the state needed for reliable communication.

If you're learning networking for CCNA, cybersecurity, SOC, firewalls, penetration testing, or network troubleshooting, understanding this properly is one of those fundamentals that keeps coming back.

We're also running a Network Engineering Live Training + Industry Project Experience for people who want to go beyond just reading networking theory and actually work through practical concepts and projects.

Training: https://training.codelivly.com/programs/network-engineering

You can enroll directly through the site, or reach out on WhatsApp: +9779815834931

If you're learning network engineering right now, you’ve probably noticed that understanding concepts is only one part of the process.

You can learn subnetting, VLANs, routing, switching, TCP/IP, DNS, DHCP, and all the other fundamentals but actually applying those concepts in a practical environment is a different experience.

That’s why I think hands-on project experience is worth prioritizing early.

Codelivly is currently running a live Network Engineering training program focused on instructor-led learning and practical industry-style projects.

Instead of just watching recorded lectures and moving on to the next topic, the idea is to learn the networking concepts and then actually work with them through practical projects.

What the program focuses on

• Live instructor-led training
• Practical networking exercises
• Industry-oriented projects
• Real-world networking scenarios
• Building practical experience alongside the theory
• Guidance throughout the learning process
• A structured path for people who don't want to jump between dozens of unrelated tutorials

I think this is particularly useful if you're trying to move from "I understand networking concepts" to "I can actually configure, troubleshoot, and work with networks."

It can also give you something more concrete to talk about when building your portfolio or preparing for networking-related interviews.

If you're currently learning networking, preparing for a networking career, or trying to get more practical experience, you can check out the program here:

Network Engineering Live Training – Codelivly

https://training.codelivly.com/programs/network-engineering

I'd recommend checking the curriculum, project details, and training format first to see if it matches what you're looking for.

For anyone learning networking: what has been the hardest part for you understanding the theory, getting hands-on practice, or finding realistic projects to work on?

A while back, I kept seeing people say they wanted to get into network engineering, but most of them were stuck in the same loop.

Watch a course → follow a few labs → forget half of it → start another course.

The missing part was actually working through networking problems and projects.

So we started putting together Network Engineering Live Training + Industry Project Experience around that idea.

Live sessions, practical work, and projects you can actually spend time working through instead of just watching someone configure a router on a screen.

We’ve opened enrollment now, but we’re keeping the number of seats limited for this round.

It’s currently 33% off as part of the launch sale.

If you've been putting off getting serious about networking, this is probably a good time to jump in:

👉 https://training.codelivly.com/programs/network-engineering

I also made a complete Network Engineer guide covering L1 → L2 → L3, if you want something to work through alongside the training:

https://resources.codelivly.com/product/network-engineer-complete-bundle-l1-l2-l3-foundations-to-advanced-architecture/

Limited seats + 33% off while the current enrollment is open.

Discord if you want to ask questions before joining:
https://discord.gg/RTZyZXATE

When a network issue comes up, these are usually the first commands I reach for.

Windows
ipconfig /all — IP, DNS, DHCP info
ipconfig /flushdns — Clear DNS cache
tracert <IP> — Trace the route
netstat -ano — Connections, ports, PIDs

Linux
ip addr — Interfaces and addresses
ss -tulpn — Listening ports/services
dig <domain> — DNS checks
curl -I <URL> — Quick HTTP response check

Cisco
show ip interface brief — Interface status
show ip route — Routing table
show mac address-table — MAC addresses
show cdp neighbors — Connected Cisco devices

For a basic issue, I normally go:

IP → gateway → target → DNS → route → interface → logs

Nothing fancy, but it saves a lot of time when you're staring at a machine wondering why nothing works.

What command do you use the most?

Discord if anyone wants to hang out: https://discord.com/invite/RTZyZXATE

✍️ If you want to become a Network Engineer, knowing Cisco commands is only the beginning.

👉 Working with Cisco routers isn’t just about configuring devices. A skilled Network Engineer must continuously verify, troubleshoot, monitor, and optimize the network.

📚 This Cisco Router Commands Cheat Sheet covers:

🔹 Basic Device Access & Configuration
🔹 Interface Configuration
🔹 IP Addressing & Routing
🔹 Static Routing & OSPF
🔹 DHCP Configuration & Verification
🔹 NAT & PAT
🔹 ACLs & Network Security
🔹 SSH Configuration
🔹 Monitoring & Troubleshooting
🔹 Useful Cisco IOS Shortcuts

💻 Essential Cisco IOS Commands:

✅ "show ip interface brief" → Check interface status and IP addresses
✅ "show ip route" → View the routing table
✅ "ping" → Test network connectivity
✅ "traceroute" → Trace the path to a destination
✅ "show running-config" → View the current configuration
✅ "show ip ospf neighbor" → Verify OSPF neighbor relationships

💡 Remember: Don’t just memorize commands. Understand what you are checking, why you are checking it, and how to interpret the output.

A good Network Engineer doesn’t simply know commands — they understand how networks work and how to troubleshoot them effectively.

👉 Save this cheat sheet for your CCNA/CCNP preparation and real-world networking practice.

🔄 Share it with someone learning Cisco Networking or preparing for a Network Engineer role.

📲JOIN US ON Discord: https://discord.gg/RTZyZXATE

If you’re trying to get into network engineering, there’s a point where watching another CCNA video isn’t going to help much.

You need to actually build a network.

That’s what I’m trying to focus on with this program.

It’s 8 weeks of live, hands-on Network Engineering training, followed by an optional 4-week practical internship.

We start from the fundamentals and work toward actually designing, configuring, securing, and troubleshooting networks.

The training covers:

• IPv4/IPv6 + subnetting
• Switching, VLANs, trunking & STP
• Static routing + OSPF
• Inter-VLAN routing + HSRP
• DHCP, DNS & NAT
• Wireless networking
• ACLs, firewalls & VPNs
• Network monitoring & troubleshooting
• Enterprise network design

And then the internship is where you take that knowledge and work through supervised network tasks — design, configuration, monitoring, troubleshooting and documentation.

No prior networking experience is required.

The next cohort starts September 14, 2026.

Current pricing is £99.99 for training or £149.98 for training + internship during the current sale.

If you're serious about moving toward a Network Engineer role and want something more practical than another course sitting in your bookmarks:

Enrollment:
https://training.codelivly.com/programs/network-engineering

Happy to answer questions about what you'll actually be doing during the training/internship.

If you’re trying to get into network engineering, there’s a point where watching another CCNA video isn’t going to help much.

You need to actually build a network.

That’s what I’m trying to focus on with this program.

It’s 8 weeks of live, hands-on Network Engineering training, followed by an optional 4-week practical internship.

We start from the fundamentals and work toward actually designing, configuring, securing, and troubleshooting networks.

The training covers:

• IPv4/IPv6 + subnetting
• Switching, VLANs, trunking & STP
• Static routing + OSPF
• Inter-VLAN routing + HSRP
• DHCP, DNS & NAT
• Wireless networking
• ACLs, firewalls & VPNs
• Network monitoring & troubleshooting
• Enterprise network design

And then the internship is where you take that knowledge and work through supervised network tasks design, configuration, monitoring, troubleshooting and documentation.

No prior networking experience is required.

The next cohort starts September 14, 2026.

Current pricing is £99.99 for training or £149.98 for training + internship during the current sale.

If you're serious about moving toward a Network Engineer role and want something more practical than another course sitting in your bookmarks:

Enrollment:
https://training.codelivly.com/programs/network-engineering

Happy to answer questions about what you'll actually be doing during the training/internship.