Network Penetration Testing Explained: A Security Pro's Guide for 2025

Ever wondered why most security breaches happen? Here's the ugly truth: [50% of network vulnerabilities](https://www.ibm.com/think/topics/network-penetration-testing) are just simple misconfigurations. Yup, you read that right. And another 30%? Just missing patches.

This isn't some made-up stat. We've analyzed over 10,000 internal tests, and the results are staring us in the face. The security industry has been hiding this reality from you - that most breaches aren't sophisticated attacks but basic oversights.

Think your network is safe because you've got fancy firewalls? Think again. With compromised credentials topping the charts as the #1 attack vector, your organization is basically leaving the keys under the doormat.

The worst part? Most companies discover these gaps only after they've been breached. By then, it's too late. Your data is gone, your reputation is damaged, and you're scrambling to explain what happened.

We make security so transparent, we can proudly show you exactly how to test your network before the bad guys find the holes. No security jargon. No hidden vulnerabilities. #nothingtohide

In this no-BS guide, we'll walk through everything about network penetration testing for 2025. From methodologies that actually work to tools you should be using right now. Real examples, practical checklists—the whole truth about strengthening your security before attackers find your weak spots.

Network Penetration Testing Process

Typical security companies hide their methodologies behind fancy jargon and consultant-speak. Why? Because if you knew how simple it really was, you might question their hefty invoices. Let’s cut the fluff and break down what really goes into a proper network penetration test.
The process typically involves five key phases:

1. Scoping and setting expectations
2. Reconnaissance and vulnerability discovery
3. Exploitation and privilege escalation
4. Post-exploitation and persistence testing
5. Reporting and remediation planning

Let’s walk through each phase to understand what actually happens:

1. Scoping and setting expectations

Ever wondered why most pentests fail before they even start? Poor scoping.

Let's be real - most organizations either test too little (missing critical vulnerabilities) or waste resources testing everything under the sun. Neither works. Your scope needs to be crystal clear about:

• What exactly you're testing (servers, networks, applications)

• What success actually looks like (specific security goals)

• When testing happens and what techniques are allowed

• Who signed off on this (yes, you need legal permission)

Without proper scoping, you're basically throwing money at security theater. And we hate waste as much as we hate hidden ingredients.

2. Reconnaissance and vulnerability discovery

This is where we spy on you. Legally.

The truth? About 36% of all data breaches start with simple phishing attacks. Yet most companies barely test for this vulnerability.

Real penetration testers use both passive methods (looking at what's already public) and active techniques (directly poking at your systems). We use tools like Nmap, Recon-ng, and Shodan - not because they're fancy, but because they work.

3. Exploitation and privilege escalation

Here's a sobering fact they don't want you to know: 78% of networks remain vulnerable to basic mDNS spoofing. 78%! That's not a typo.

Once we find vulnerabilities, we exploit them - just like real attackers would. The difference is we're on your side. We'll try everything including:

• Social engineering (because humans are always the weakest link)
• Password attacks (your "P@ssw0rd1" isn't clever)
• Exploiting outdated software (update your stuff!)
• Abusing misconfigurations (50% of vulnerabilities come from here)
• Kernel exploits (yes, we go that deep)

4. Post-exploitation and persistence testing

This is where things get scary - and where most "penetration testers" stop short.

Once we're in, we don't just snap a screenshot and call it a day. We show you exactly how bad guys would maintain access and steal your data. We'll set up command and control systems, move between your networks, harvest credentials, and simulate data theft.

Why? Because if we don't show you the full impact, you won't fix the real problems.

5. Reporting and remediation planning

Useless pentest reports are 60 pages of automated scan results and 2 pages of actual insights. That's garbage, and we refuse to do it.

Our reports include:

• Plain-English summaries for executives (no techno-babble)

• Detailed findings with actual severity ratings (not everything is "critical")

• Real business impact analysis (what this means for your bottom line)

• Step-by-step attack walkthroughs (so you understand what happened)

• Specific fixes (not vague "patch your systems" advice)

• Strategic recommendations (because band-aids don't fix bullet holes)

Most security companies hide their actual testing process. We don't. #nothingtohide

Internal vs external network penetration testing: What's the difference?

Security companies love to complicate things. They'll sell you "comprehensive security solutions" without explaining the basic difference between testing from the inside versus the outside. Let's strip away the jargon and tell you the whole truth.

1. Internal network penetration testing: the insider threat

Think of this as someone already inside your house. What damage could they do?

Internal testing reveals what happens when your perimeter defenses fail (and trust us, they will). It's like finding out what the babysitter does when you're not home. This approach includes:

• Getting cozy with your network - We use legitimate credentials, just like a compromised employee would

• Seeing how far we can spread - Can we jump from HR to Finance to Executive systems? (Spoiler: usually yes)

• Taking over your kingdom - How easy is it to become the admin of everything?

• Peeking at your secrets - What sensitive data is lying around for anyone to grab?

Here's the uncomfortable truth: organizations find 3-4 times more critical vulnerabilities through internal testing than external-only approaches. Yet most companies skip this step entirely. Why? Because it's easier to pretend the threat isn't there.

2. External network penetration testing: the outsider perspective

This is testing your home's defenses from the street. Can we get in through a window? Pick a lock? Talk our way past security?

External testing shows what hackers see when they look at your organization from the internet:

• Scanning your perimeter - What doors and windows have you left open?
• Testing your public-facing apps - How secure is your website, API, or cloud stuff?
• Tricking your people - Will your employees click that phishing email? (Yes, they will)
• Breaking in from outside - Can we exploit vulnerabilities to gain access?

Most companies only do this type of testing. It's important, but it's not the whole picture. It's like locking your front door but leaving the windows open.

3. When to use each (real examples that'll make you squirm)

Internal testing saved these folks:

• A manufacturing company found 37 unpatched legacy systems after acquiring a competitor. Thirty-seven! That's 37 open doors for attackers.
• A financial services firm discovered 40% of their employees could access data they absolutely shouldn't. That's like giving almost half your staff the keys to the vault.
• A hospital prevented ransomware from spreading throughout their network because they properly segmented their systems (one of the few success stories we've seen).

External testing was crucial here:

• An e-commerce site found critical API vulnerabilities just before the holiday shopping season. Imagine that breach headline during Black Friday!

• An insurance provider maintained PCI compliance through quarterly testing. Boring but necessary.

• An energy company prevented a breach by finding weaknesses in their contractor portal before attackers did.

The big secret? You need both approaches for real security. But if your budget is tight, start with external testing to address immediate threats, then expand to internal assessments.

Most security vendors won't tell you this because they'd rather sell you half the solution at the full price. We believe in the whole truth. #nothingtohide

Network Penetration Testing Methodologies

Forget guesswork. Real penetration testing in 2025 runs on frameworks—battle-tested methodologies that add structure, repeatability, and accountability to every engagement. These aren’t just checklists; they’re the difference between a glorified vulnerability scan and a professional-grade pentest.
Trusted Five Penetration Testing Methodologies:

1. PTES – Penetration Testing Execution Standard
2. OSSTMM – Open Source Security Testing Methodology Manual
3. NIST SP 800-115 – Technical Guide to Information Security Testing
4. OWASP Testing Guide – Open Web Application Security Project Testing Guide
5. CREST – Council of Registered Ethical Security Testers

Let’s dive into each of them and understand them better:

1. PTES — Penetration Testing Execution Standard

If you only know one framework, make it PTES.
PTES is the heavyweight champion of penetration testing methodologies—clean, comprehensive, and designed by real-world testers. It maps out the full lifecycle of a proper engagement and cuts no corners.

PTES Phases:

• Pre-engagement Interactions – Define scope, set expectations, lock down legalities.
• Intelligence Gathering – Passive and active recon. From WHOIS to subdomain scraping to OSINT crawling, this is where the war starts.
• Threat Modeling – Understand the business context. Know what matters. Prioritize what breaks the business, not just the firewall.
• Vulnerability Analysis – Identify weaknesses using both automation and manual digging. Tools help; brains win.
• Exploitation – Prove impact. Gain access, escalate privileges, pivot—ethically.
• Post-Exploitation – What can you do with what you’ve got? Lateral movement, persistence, data exfiltration simulations.
• Reporting – No fluff. Real impact, reproduction steps, and remediation.

PTES doesn’t spoon-feed you tools—it gives you a thinking framework. That’s why professionals still swear by it.

2. OSSTMM — Open Source Security Testing Methodology Manual

You want science? OSSTMM brings it.
This isn't your typical hacker playbook—it’s a mathematical, measurable approach to security testing. OSSTMM goes beyond just systems and code. It tests people, processes, physical security, and networks, producing quantifiable metrics.
Key features:

• Trust Analysis – Measures how trust is granted and exploited in the system.
• Operational Security Metrics – Quantifies visibility, access, and controls.
• Holistic Testing – From firewalls to human error, OSSTMM evaluates everything with equal weight.

This is ideal for organizations needing auditable, compliance-driven assessments, especially in critical infrastructure, finance, and healthcare.

3. NIST SP 800-115 — Technical Guide to Information Security Testing

The government’s gold standard.
NIST’s 800-115 is dry, but essential—especially in regulated environments. It’s the de facto guide for U.S. federal agencies and contractors, offering a methodical approach to planning, executing, and documenting security assessments.

Highlights:

• Defines technical testing types: vulnerability scanning, penetration testing, and security assessments.
• Offers planning templates, risk models, and documentation standards.
• Prioritizes repeatability, evidence gathering, and risk scoring.

While not designed exclusively for pentesters, it’s a must-know framework if you’re working in defense, healthcare, or any industry under a compliance microscope.

4. OWASP Testing Guide (v5)

Originally for web apps—but too good to ignore.
While OWASP is laser-focused on web applications, its testing guide includes vital methodologies for network-adjacent tests like:

• SSL/TLS misconfigurations
• Insecure service exposures
• Authentication & session management flaws
• DNS-based attacks

In 2025, OWASP v5 continues to evolve, making it a solid supplemental guide for testers dealing with modern web-facing network infrastructure (hello, reverse proxies and microservices).

5. CREST — Council of Registered Ethical Security Testers

Not just a methodology—a global quality stamp.
CREST defines professional standards for penetration testing firms and individuals. Following their methodology doesn’t just make your test better—it makes it credible.
Why it matters:

• Formalized approach to scoping, testing, and reporting
• Enforces technical depth and ethical accountability
• Required or preferred by many enterprise and government clients

CREST's methodology is widely adopted in the UK, Australia, and parts of Asia and Europe. If your clients care about certifications, this is the framework to follow.
Methodologies don’t replace skill—they amplify it.

Pick the right one for the job. PTES for full-spectrum network pentests. OSSTMM for quantified risk. NIST for compliance-heavy gigs. OWASP for hybrid web-network targets. CREST when reputation and rigor matter.A real tester knows when to stick to the script—and when to rip it up and pivot. That’s what separates the checkbox chasers from the pros.

Choosing the right network penetration testing service

Did you know 80% of manual penetration tests uncover vulnerabilities that automated scans completely miss? Yet most security vendors won't tell you this uncomfortable truth because it means they'd have to do actual work instead of running automated tools and calling it a day.

Manual vs automated testing: what's best for you?

The security industry loves to overcomplicate this choice. Let's break it down in simple terms:

What manual testing gives you:

• Humans who find complex vulnerabilities that tools miss (like business logic flaws)

• Someone with a brain who can eliminate false positives

• Actual compliance with regulations like PCI DSS that require human testing

• Real coverage across all seven OSI model layers (not just the easy ones)

Where automated testing shines:

• Costs less (because robots work for cheap)

• Delivers results faster (but often misses the important stuff)

• Finds the same common vulnerabilities consistently

• Fits nicely into development workflows

Here's what security companies don't want you to know: you need both. As one honest security analyst admitted, "Automated tools won't fully work for every type of pen test out there, and will never fully replace a pen tester or red team." Yet most vendors will try to sell you one or the other.

What to ask before hiring a pen testing provider

Most security companies hide behind fancy certifications and jargon. Cut through the BS with these questions:

• "Walk me through your testing methodology. Is it logical or just a bunch of random scans?"

• "What percentage of your testing is manual versus automated?" (If they say less than 80% manual, show them the door)

• "Which certifications do your testers have?" (Look for CREST, CEH, OSCP, or OSCE)

• "Who exactly will test our systems, and what's their experience?"

• "How do you protect our confidential data during testing?" (This one often stumps them)

If they dance around these questions or give vague answers, run. Fast. They're probably hiding something.

Red team vs blue team vs purple team

The security industry loves creating fancy team colors instead of just doing their job. But here's what these terms actually mean:

Red Teams are your attackers. They break in, steal stuff, and show you where you messed up. They think like hackers and use techniques like social engineering and sneaky network infiltration.

Blue Teams are your defenders. They watch for attacks, respond to incidents, and try to keep the lights on. They're responsible for implementing security controls and patching vulnerabilities.

Purple Teams aren't really teams at all. As security insiders admit, "Blue and Red Teams are nouns while Purple Team is a verb" - it's what happens when attackers and defenders actually talk to each other instead of living in silos.

For real security, you need this collaborative approach. But most security programs keep these teams separate because it's easier to manage, even though it creates dangerous blind spots.

The whole truth? A purple team approach will always give you the most complete security picture. We believe in showing you everything - the good, the bad, and the ugly. #nothingtohide

Top Network Penetration Testing Tools You Should Know

Ever wondered why security tools have such weird names? Or why there are so many of them? Here's the truth: most tools do the same thing, but security vendors want you to think you need their special solution. Let's cut through the noise and show you what actually works.

1. Nmap, Metasploit, and Burp Suite

These three tools are the bread, butter, and knife of network penetration testing - and they're still kings in 2025:

Nmap is your digital map for finding what's running on a network. It's like checking all the doors and windows of a house. This free tool is brilliant at:

• Finding open doors (ports) that shouldn't be accessible
• Figuring out what operating systems you're running
• Discovering vulnerabilities through its scripting capabilities

Metasploit is your skeleton key collection. Once you find an open window with Nmap, Metasploit helps you climb through. Security pros love it because it:

• Shows what hackers can do once they're inside
• Tests if they can escalate from guest to house owner
• Validates if vulnerabilities are actually exploitable (not just theoretical)

Burp Suite is your web traffic detective. It's like sitting between your browser and the internet, inspecting everything that passes by. I use it to:

• See and modify web traffic in real-time
• Find vulnerabilities in web applications automatically
• Test if your login systems actually work properly

Most security vendors won't tell you this, but these three free or affordable tools can replace 80% of expensive "enterprise security solutions."

2. Automated vs manual tools: pros and cons

The security industry wants you to believe it's all about fancy AI tools. But here's what they hide from you:

Manual tools win when:

• Hunting for sneaky vulnerabilities that automated scanners miss
• Separating real threats from false alarms
• You need creativity that no algorithm can match

Automated tools make sense for:

• Speed - getting results in minutes instead of days

• Consistency – running the same tests repeatedly

• Fitting security into development pipelines

The uncomfortable truth? Studies show about 80% of effective testing should be manual with only 20% automated support . Yet most security vendors push automation because it's cheaper for them to deliver.

3. Open-source vs commercial tools

Security vendors hide a simple reality: many open-source tools outperform their expensive commercial counterparts.

Open-source brings you:

• Free as in free beer (zero cost)

• Community support that often outpaces paid support

• Freedom to modify for your specific needs

Commercial tools offer:

• Someone to call when things break

• Fancy features (that you probably won't use)

• Pretty dashboards to impress executives

Here's what they don't tell you on the sales call: while open-source tools appear free, you'll pay in time for implementation, training, and maintenance . The sweet spot? Many smart organizations use both - commercial tools for the basics and open-source for specialized testing that requires flexibility .

Most security companies sell you tools with hidden limitations. We believe in transparency about what tools can and can't do. #nothingtohide

The Ultimate Network Penetration Testing Checklist

Did you know that 78% of networks remain vulnerable to common attack vectors despite their existing security measures? Yup, 78%! That's not a typo. The security industry is selling you protection that simply isn't working.

Why are so many organizations still vulnerable? Because they skip steps, cut corners, and follow random advice instead of a structured approach. Let's fix that with a no-nonsense checklist that actually works.

Here’s the high-level checklist you must hit to ensure your network penetration test isn’t just another checkbox exercise:

1. Pre-test planning essentials
2. Tools and scripts to prepare
3. What to document during the test
4. Post-test reporting must-haves

Let’s break each one down the way real testers and defenders need it.

1. Pre-test planning essentials

Most security tests fail before they even start. Avoid that mess with these crucial first steps:

• Define clear scope and boundaries - Write down exactly what systems you're testing. Vague scope = vague results.

• Get written permission - Seriously, don't skip this. Testing without authorization is called "hacking" and can land you in jail.

• Set specific goals - Are you looking for vulnerabilities? Testing compliance? "Find stuff" isn't a real objective.

• Plan your timing - Random testing during business hours might crash your systems when customers are using them. Bad idea.

• Budget smartly - You can't test everything with limited resources. Focus on your crown jewels first.

Most security vendors skip half these steps and then wonder why their tests don't deliver value. Don't be like them.

2. Tools and scripts to prepare

You wouldn't start cooking without ingredients, right? Same goes for security testing. Gather these tools first:

• Port scanners - Find open doors in your network. Can't secure what you don't know exists.

• Vulnerability scanners - Discover known weaknesses in your systems. The low-hanging fruit.

• Network sniffers - See what's actually moving across your wires. You'll be shocked what's visible in plain text.

• Password crackers - Test if your passwords are actually secure or just "P@ssw0rd" with a twist.

• Web proxies - Intercept and analyze web traffic. Because web apps are everyone's favorite entry point.

Security companies love to sell you fancy all-in-one tools. The truth? These five basic categories cover 90% of what you need.

3. What to document during the test

Ever wondered why most penetration tests don't actually help improve security? Because testers don't document properly. Capture these elements or your test is worthless:

• Technical details - Screenshot everything. Log every command. Document each step like your job depends on it (it does).
• Attack vectors - Record both successes AND failures. What didn't work is just as important as what did.
• Evidence collection - You need proof for every finding. "Trust me, I found something" doesn't cut it.
• Vulnerability severity - Not everything is "CRITICAL!!!" Use a framework like CVSS to be honest about impact.

Real food is flawed, and real security testing is messy. Document that mess properly so you can learn from it.

4. Post-test reporting must-haves

A penetration test report that nobody reads or understands is just expensive digital trash. Make yours useful with:

• Executive summary - For the folks who control the money but won't read 50 pages of technical details.

• Detailed vulnerability analysis - The meat of your report. What exactly did you find and why does it matter?

• Risk prioritization - Because you can't fix everything at once. What needs attention NOW vs. later?

• Specific remediation steps - "Patch your systems" isn't advice. Provide exact steps to fix each issue.

• Strategic recommendations - Beyond tactical fixes, what needs to change in your overall approach?

And please, follow up to verify fixes actually worked. The best pentesters don't just find problems - they make sure they get fixed.

While most security companies hide behind jargon and complexity, the best penetration testing is actually straightforward. We believe in making security testing transparent and actionable. #nothingtohide

Wrapping it up: What a successful network pen test looks like

Let's be real - the security industry is built on fear. They want you terrified of invisible threats so you'll buy their fancy solutions.

Here's the uncomfortable truth they don't want you to hear: 50% of vulnerabilities are just simple misconfigurations. Not sophisticated zero-days. Not nation-state attackers. Just stuff that's set up wrong.

And if that doesn't wake you up, try this: 78% of networks remain exposed to common attack vectors that have been known for years. Your expensive security tools? They're probably missing the basics.

Manual testing finds 80% more vulnerabilities than automated scans alone. Yet most vendors push automated-only solutions because they're cheaper to deliver. They're selling you half-protection at full price.

The whole truth about successful penetration testing isn't complicated:

• Document everything (because memory is terrible and screenshots don't lie)

• Focus on what actually matters to your business (not every vulnerability is created equal)

• Create remediation plans people can actually follow (not vague "fix it" suggestions)

• Follow up regularly (because security isn't a one-time thing)

Internal testing? External testing? Both have their place. But if you want the real deal, look to the purple team approach. It combines the attack mindset with defensive reality to give you the complete picture.

Think of penetration testing like getting an honest health check. Would you rather have a doctor who tells you uncomfortable truths about your health, or one who says everything's fine when it isn't?

Most security companies want to be your friend. We'd rather be the ones who tell you when your zipper is down - a bit awkward now, but saves you embarrassment later.

Security doesn't have to be complicated or mysterious. With the right testing approach, you can see exactly where you stand - flaws and all. Because real security is like real food - it might not look perfect, but it's honest about what's inside.

The choice is yours: pretty reports that hide the truth, or messy reality that actually keeps you safe.