Network & Security

Get Discount

This is the best Udemy Linux Security: The Complete Iptables Firewall Guide coupon code discount for 2025.

So if you’re interested in Andrei Dumitrescu, Crystal Mind Academy’s “Linux Security: The Complete Iptables Firewall Guide” course, which will help you increase your IT & Software skills, get your discount on this Udemy online course up above while it’s still available. (The coupon code will be instantly applied.)

Linux Security: The Complete Iptables Firewall Guide review for 2025

In our review of this course, we try to help you answer all of your most important questions about Linux Security: The Complete Iptables Firewall Guide as quickly and efficiently as possible, so that you can determine whether this online education training is worth your time and money.

Feel free to jump to whatever question you want answered the most.

Here’s what you’ll learn:

Why use LSTCIFG as an abbreviation of the course name?

During our Linux Security: The Complete Iptables Firewall Guide course review, you might sometimes see us refer to it as LSTCIFG for the following 2 reasons:

1. We created the acronym by taking the first letter of every word (which was very ingenious and innovative, we know)
2. We’re lazy and LSTCIFG is simpler and easier for reviewing purposes

The full course name is 52 characters long, including blanks, while LSTCIFG is 7 characters long.

You do the math.

Okay, we’ll do the math. We’re saving 45 characters every time we use LSTCIFG.

So, just a heads up that we’ll be using this abbreviation sometimes, so you’re not left scratching your head and wondering what the heck we’re talking about whenever we refer to LSTCIFG throughout the remainder of this review.

Is the Linux Security: The Complete Iptables Firewall Guide course for you?

To determine whether Andrei Dumitrescu, Crystal Mind Academy’s Udemy course is a good fit for you or not, ask yourself the following questions down below.

The more you answer “yes” to each question, the more likely it is that you’ll like this course.

Can you understand what Andrei Dumitrescu, Crystal Mind Academy’s course is about in 30 seconds or less?

Hopefully, you can easily grasp in 10 seconds or less what this online course is about simply by taking a look at the title that Andrei Dumitrescu, Crystal Mind Academy chose for the course, “Linux Security: The Complete Iptables Firewall Guide”, as well as its subtitle: “Linux Security Improved. Create professional Netfilter/Iptables Firewalls. All you need to know about Netfilter/Iptables”.

This combo of title and subtitle should be enough to communicate the purpose of the training if Andrei Dumitrescu, Crystal Mind Academy is a good, clear communicator (which, of course, you want in a teacher).

In our opinion, if you still don’t know what LSTCIFG is about after looking at these two things, then this is a red flag, and you might be better off not taking this class.

Among other things, it means Andrei Dumitrescu, Crystal Mind Academy hasn’t clearly and accurately conveyed what the course is about and might not be the best teacher for you.

For similar reasons, it’s important that you’re able to clearly understand what Linux Security: The Complete Iptables Firewall Guide is all about from the first few lines of the course description.

So take just a few seconds to read the opening lines down below and see what you think of them. 

Opening lines of Andrei Dumitrescu, Crystal Mind Academy’s official description of LSTCIFG

***Fully updated for 2020*** This Iptables course covers every major topic related to Netfilter and Iptables including Ipset, Advanced Matches and Targets, NAT, Fort Forwarding, User-Defined Chains and many more!

Welcome to the most complete and up-to-date course for learning and using Netfilter & Iptables Linux Firewall, taught by a DevOps Engineer and Professional Trainer.

Just starting out with Linux Security and Iptables? Perfect. This course starts out assuming you’re new to Netfilter, Iptables and Linux Firewalls.

(Read more about this course on the official course page.)

Does LSTCIFG pass the 30 Seconds Test?

You can read a lot more about Linux Security: The Complete Iptables Firewall Guide on the official course page on Udemy, but the point is this: are the title, subtitle, and just the first few lines of the description enough to help you understand what the course is about?

If so, Andrei Dumitrescu, Crystal Mind Academy has done a good job and can be considered more trustworthy and a good communicator, which are important qualities for any teacher.

And, if not, maybe you’re better off looking at other IT & Software classes that are more clearly defined and more tailored to your specific interests.

Did Linux Security: The Complete Iptables Firewall Guide appeal to you in 30 seconds or less?

Now that you’ve done the 30 Second Test with LSTCIFG above, what is your gut reaction to this IT & Software course with only the basic information of its title, subtitle, and the first few opening lines of its official course summary?

Did Andrei Dumitrescu, Crystal Mind Academy do a good job conveying its subject matter, and did it immediately get your attention and appeal to you?

If so, Andrei Dumitrescu, Crystal Mind Academy’s online course is certainly worth considering some more.

But if not, perhaps it’s in your best interest to consider some other IT & Software courses instead, because clear communication and being able to hook and maintain your interest are two very important qualities for your online learning success.

Does Andrei Dumitrescu, Crystal Mind Academy sound like a course instructor you’d like to learn from?

You’ve already learned how to use The 30 Second Test to make a quick evaluation of whether the LSTCIFG course is worth taking.

We have a similar 15 Second Bio Test where you read only the first few lines of an instructor’s background — in this case, Andrei Dumitrescu, Crystal Mind Academy’s background — and then you make a quick, snap judgment as to whether you think the instructor would be ideal for you.

There is no right or wrong answer. It’s just about going with your gut instinct. What might appeal to one potential student might alienate another, and vice versa.

(FYI, all Udemy instructors, including Andrei Dumitrescu, Crystal Mind Academy, have a Udemy profile on their course page, so you can easily check for a bio and background on the Udemy website that way. We’re only including the first few lines of the bio down below for The 15 Second Bio Test).

Opening lines from Andrei Dumitrescu, Crystal Mind Academy’s Udemy bio

I’ve been a Network and Software Engineer for over 15 years, the typical profile of a DevOps Engineer.

What did you think about Andrei Dumitrescu, Crystal Mind Academy after reading just the first few lines of the bio above?

After reading just the first few lines about Andrei Dumitrescu, Crystal Mind Academy, did it make you more or less interested in taking the LSTCIFG course?

And did it make you feel like Andrei Dumitrescu, Crystal Mind Academy was more or less credible and qualified to teach Linux Security: The Complete Iptables Firewall Guide?

Finally, overall, did you feel like you’d receive the proper training from the instructor of this IT & Software course?

As always, we encourage you to listen to your gut instinct, which is different for every student.

Are the LSTCIFG lessons clear, specific, and organized well?

Part of the (good) problem with Udemy’s online courses, such as the Linux Security: The Complete Iptables Firewall Guide course, is that the instructors are constantly updating them, including adding and renaming lessons.

So it makes no sense whatsoever for us to list out all the modules and lessons in the LSTCIFG course here, because you can just as easily go to the Udemy course page and get all the up to date course structure as of right now.

We do, however, have some tips about reviewing Andrei Dumitrescu, Crystal Mind Academy’s course structure, so that you can get a better sense of whether this program is worth your time or not.

In a nutshell, you want to scan the the titles of the different sections and lessons of the course, and verify that they are clearly relevant to the course’s name, Linux Security: The Complete Iptables Firewall Guide, as well as the course’s subtitle, Linux Security Improved. Create professional Netfilter/Iptables Firewalls. All you need to know about Netfilter/Iptables.

If the section names and lessons are clear, specific, and relevant, then it’s a good sign that LSTCIFG is potentially a good, useful course for you, and you can have more confidence in Andrei Dumitrescu, Crystal Mind Academy’s teaching abilities and lesson planning.

On the other hand, if the module names are confusing, vague, or irrelevant, then this is a red flag, which might indicate that the program is worth skipping.

Have you taken some free lessons from Andrei Dumitrescu, Crystal Mind Academy that you enjoyed?

Have you already learned something from Andrei Dumitrescu, Crystal Mind Academy that you valued or enjoyed?

For example, does the Linux Security: The Complete Iptables Firewall Guide training have some free lessons that you can try? (Almost all Udemy instructors will give you at least one or two lessons for free to help you make a better, more informed decision before enrolling in their course.)

But if you weren’t able to get any LSTCIFG lessons for free, have you perhaps watched a YouTube video by Andrei Dumitrescu, Crystal Mind Academy, or perhaps come across this instructor’s thoughts on Quora, Facebook, LinkedIn, Github, Reddit, or some other platform?

Or have you perhaps even taken one of Andrei Dumitrescu, Crystal Mind Academy’s free courses or free webinars? (Many online teachers offer these freebies, which is a great way to get to know them and evaluate their teaching methods before buying one of their courses.)

In any case, the more familiar you are with Andrei Dumitrescu, Crystal Mind Academy’s teaching methods, and the more you enjoy them, the more likely it is that Linux Security: The Complete Iptables Firewall Guide will be a good fit for you.

(P.S.: We strongly encourage you to seek out some free instruction from Andrei Dumitrescu, Crystal Mind Academy before purchasing this course, since it’s one of the best ways to determine whether LSTCIFG will be helpful for you.)

Are “Linux Security: The Complete Iptables Firewall Guide” reviews generally positive?

On the bottom of the LSTCIFG page, you can read student reviews of the class.

Prior to August 24, 2025, there were 3,058 students enrolled, 470 reviews / ratings, and it was overall rated 4.6 out of 5.

Obviously, the more highly other students rate LSTCIFG the better, but no matter what, keep an open mind when reading the reviews, since you might still like a course a great deal that other students dislike.

After all, everyone’s got their own opinion.

We recommend that you spend only a couple minutes scanning the LSTCIFG reviews to get an overall sense of them. You don’t have to read each one!

Is Andrei Dumitrescu, Crystal Mind Academy responsive to student questions in the LSTCIFG training?

You can see what other students have to say about this in their LSTCIFG reviews.

But, our simple all time favorite way of gauging an instructor’s responsiveness is to simply email the instructor and see if or how they respond.

In this case, Udemy has a messaging system for students / anyone who has an account, and you can send Andrei Dumitrescu, Crystal Mind Academy a message through this system quite easily, even if you haven’t bought LSTCIFG yet.

For example, you could say, “Hi, and I came across LSTCIFG while looking at IT & Software courses on Udemy. If I enroll in your training, would you mind if I asked you any questions along the way?”

If you use this approach, the response (or lack of response) from the professor will tell you everything.

Obviously, the quicker the response the better!

Are you comfortable going through the lessons in Linux Security: The Complete Iptables Firewall Guide on your own, online?

This is a big one, because Linux Security: The Complete Iptables Firewall Guide is an online course as opposed to a course that you physically take in a classroom.

Of course, you will need a good internet connection to have access to the course material and lessons, but beyond that, you also have to be comfortable being self motivated to some degree, being on your own, and not having any physical interaction with any of the other students taking Linux Security: The Complete Iptables Firewall Guide.

Yes, you will be able to interact with the students and the teacher, Andrei Dumitrescu, Crystal Mind Academy, online, but it’s a different kind of experience than what you’d get if you were interacting with them in person.

This is not a big deal to most people, but it might be something for you to consider if you feel like you do better taking classes in person rather than learning online.

Do the pros / benefits of LSTCIFG make it worth your time?

Ideally, if you’ve gone through the evaluation steps above, you have a list of positive things about the Linux Security: The Complete Iptables Firewall Guide training that looks something like this:

• The purpose of LSTCIFG can be clearly grasped and understood, and its lesson structure is clear, specific, and well organized
• Andrei Dumitrescu, Crystal Mind Academy is well qualified to teach this subject matter, has good teaching abilities, and is responsive to student questions
• Other LSTCIFG students have great things to say about the program

Other benefits include:

• You get to go through LSTCIFG at your own pace
• You join a community of 3,058 other students taking the course
• You get lifetime access to the training
• All updates to the training are free
• You have a 30 day money back guarantee

Even if there are some things that you don’t like about the program, so what?

The question is simply this: do you think that LSTCIFG would be worth your time, even if there are some things that could be better about it?

Can you comfortably afford LSTCIFG?

Can you comfortably afford the cost of Linux Security: The Complete Iptables Firewall Guide?

This is an important question to answer, because even if you think LSTCIFG sounds like the greatest online class in the world, it’s still not worth taking if you can’t comfortably afford it!

Before August 24, 2025, the price was $12.99 before any Udemy discount, and you were able to pay with a credit card.

Keep in mind that this is a Udemy online course, and there’s a great chance that you can get a solid discount on LSTCIFG with Udemy coupons / promo codes, especially with the strategies we provide for helping you find the best, most popular coupons available.

We’ll cover that in greater detail in the next section, because at the end of the day, its important that you can learn whatever you want to learn without getting into a lot of credit card debt.

How can you maximize your discount on Linux Security: The Complete Iptables Firewall Guide?

By far, the easiest way to get the best and biggest discount on this course is to use the Linux Security: The Complete Iptables Firewall Guide discount code link at the top of this page.

It will instantly give you the best coupon code we could find for Andrei Dumitrescu, Crystal Mind Academy’s online training.

We don’t believe there’s a bigger discount than the one we provided, but if for some reason you’d like to try find one, you can use the methods below to hunt for the best LSTCIFG course coupons and promo codes you can find.

FYI, the methods below will help you not just with getting LSTCIFG for a better price, but also with any other Andrei Dumitrescu, Crystal Mind Academy Udemy course that you’d like to get for cheaper.

How can Google help you get a LSTCIFG discount?

To use this method, do a Google search for the LSTCIFG training, but in your search query, be sure to add words like coupon code, promo code, deal, sale, discount, and Udemy.

For example, you might do a search for “Udemy Linux Security: The Complete Iptables Firewall Guide promo code” or “Linux Security: The Complete Iptables Firewall Guide udemy coupon codes” and see what turns up.

Similarly, you can use the same combination of search terms with Andrei Dumitrescu, Crystal Mind Academy’s name and see what happens.

For example, you might do a Google search for “Andrei Dumitrescu, Crystal Mind Academy Udemy coupons” or “Andrei Dumitrescu, Crystal Mind Academy course coupon codes” and see if that helps you.

However, in general, it’s far more powerful to do a search for deals and coupon codes with the actual training’s name, than with the instructor’s name.

So in this case, for example, prioritize searches for “Linux Security: The Complete Iptables Firewall Guide coupons” rather than “Andrei Dumitrescu, Crystal Mind Academy coupons”.

How can a Udemy sale get you LSTCIFG for cheaper?

Every once in while, Udemy will do a sitewide sale where they offer all (or almost all) their courses at a discounted price. For example, one of the best sales is where every course is only $10 or $9.99.

So, if you’re interested in saving as much money as possible, you could wait and see if you can get LSTCIFG for this cheaper Udemy sale price one day.

The problem is that these sales only occur sporadically, so you might be waiting for a while. Also, if Andrei Dumitrescu, Crystal Mind Academy decides not to participate in the site wide sale, then you won’t get a discount on LSTCIFG, even though you could get a great discount on almost any other class at Udemy!

To understand this, think of there as being two different coupon categories for the LSTCIFG course. Category one is an official Udemy coupon (which instructors can opt out of), while category two is a coupon offered directly by the instructor.

At the end of the day, it doesn’t matter what kind of a coupon tag you’re dealing with (for example, “officially from Udemy” or “officially from the instructor”), as long as long as as you’re dealing with active coupons that get you a better price.

How can you get a LSTCIFG discount from Andrei Dumitrescu, Crystal Mind Academy?

If you’re really serious about getting “Linux Security: The Complete Iptables Firewall Guide” for the cheapest price possible, then perhaps one of the most powerful things you can do is get a coupon code straight from Andrei Dumitrescu, Crystal Mind Academy, instead of waiting for a Udemy sale.

To do this, you can use either the direct approach or an indirect approach to try to get your discount.

With the direct approach, the big idea is to simply get Andrei Dumitrescu, Crystal Mind Academy’s contact info in some way or another (whether it’s email, or Twitter, or whatever else).

Then you send a message saying something like “I’m interested in enrolling in Linux Security: The Complete Iptables Firewall Guide. Do you happen to currently have an active coupon code for it that I could use?” (And then, hopefully, you’ll get a reply with your discount code.)

On the other hand, with the indirect approach, you join Andrei Dumitrescu, Crystal Mind Academy’s mailing list, if you can find it, and then you hope that at some time LSTCIFG will be promoted to you at a discount.

By far, the more powerful approach is the direct approach, because it tends to get results faster. But you can experiment with the indirect approach and see if it works for you.

Can you get LSTCIFG for free?

Of course, the best possible price for the LSTCIFG training is free! As in, you pay no money whatsoever.

And guess what? Sometimes Udemy instructors provide coupon codes that enable students to take their courses for free. So, perhaps it’s possible that Andrei Dumitrescu, Crystal Mind Academy has done this.

Basically, if you’re trying to get this program for free, you will want to search for the course’s name along with other words like free coupon, or 100 off coupon.

For example, you might do a google search for “Linux Security: The Complete Iptables Firewall Guide free coupon” or “Linux Security: The Complete Iptables Firewall Guide 100 off coupon” and see what happens.

But keep this in mind: often, Udemy teachers will offer a free coupon for their course when it first opens to get some publicity and reviews. And then, after a few days, they’ll make the coupon expired.

So even Andrei Dumitrescu, Crystal Mind Academy has offered free coupons for LSTCIFG in the past, the odds are likely they will all be currently expired. This is a common pattern that we have found.

What about a LSTCIFG free download?

It’s important to understand that there’s a difference between getting full access to the LSTCIFG training for free legally with a free coupon code vs. finding a way to download LSTCIFG illegally.

If you really want to go the download route, you can do a google search for something like “Linux Security: The Complete Iptables Firewall Guide download”.

And if that doesn’t get you the results you want, you can add the word “free” to your search.

For example, perhaps you could do a google search for “Linux Security: The Complete Iptables Firewall Guide free download”.

However, even if you get some results from these searches, we do not recommend that you take this course of action.

First of all, there are some shady sites out there that could be trying to infect your computer.

Second, Andrei Dumitrescu, Crystal Mind Academy created this course and deserves monetary compensation for it.

And third, if you go the free download route, you’ll be missing out on a lot of value, because you won’t be able to ask the instructor questions or interact with the other 3,058 students enrolled in the program.

Can you get a refund on Linux Security: The Complete Iptables Firewall Guide if you don’t like it?

Let’s say that you used our tips above, and you were able to buy the LSTCIFG training at a fantastic discounted price. So at this point, you’re super excited.

Then, you actually dive into Andrei Dumitrescu, Crystal Mind Academy’s course, and you discover that it just isn’t for you for whatever reason.

And now you’re super bummed, because you feel like it wasn’t money well spent.

Well, guess what?

Udemy offers a rock solid 30 day money back guarantee on all their courses, so you can get a refund on LSTCIFG no matter what. And this means there is absolutely no risk.

Indeed, even if you left a super negative, critical review on the LSTCIFG training, and then asked for your money back, you’d get a refund. For better or worse, there’s nothing Andrei Dumitrescu, Crystal Mind Academy could do about it, since it is simply Udemy policy.

To sum it up: yes, you can get a full refund, so at the end of the day, don’t worry about the possibility of purchasing LSTCIFG and not liking it, since you can always get your money back.

What is OCP’s overall rating of Linux Security: The Complete Iptables Firewall Guide?

During this LSTCIFG review, you’ve learned about some of the unusual ways we like to evaluate courses, such as with The 30 Second Test and The 15 Second Bio Test.

So our overall review process is perhaps a little unusual and different from other reviews out there. Keep this in mind when you consider the overall rating / score that we have given this course.

Anyway, after taking a look at the LSTCIFG training, the instructor, Andrei Dumitrescu, Crystal Mind Academy, and reading what other students have said about this program, we give it an overall rating of 4.9 out of 5.

Ultimately, though, what matters most is what you would rate it based on the same criteria.

What are some potential alternatives to Linux Security: The Complete Iptables Firewall Guide?

If you like this course, you might also be interested in:

1. UIPath RPA Tutorial – Zero To Advanced RPA UIPath Developer

Start your RPA Journey from Zero to Hero with UIPath

Taught by Shahansha Shaik

2. Finance 101: Financial Skills for the Real World

Understand and Learn How to Apply the Core Principles of Finance In a Couple of Hours

Taught by 365 Careers

3. Excel, Fin Analysis, Valuation and Financial Modeling 2019

Learn Excel for Finance, Financial Analysis, DCF and Relative Valuation and Financial Modeling from scratch.

Taught by Institute of Investment Banking

4. An Introduction to Reliability Engineering

A Study of Why Things Fail and How to Measure and Improve their Useful Life

Taught by Ray Harkins

5. The Complete Google Ads Masterclass (Former Google AdWords)

Learn Google Ads (Former Google AdWords) to Get More Traffic, Leads & Sales to Grow Your Business & Career.

Taught by Robin & Jesper

TLDR: Just the quick facts about LSTCIFG

Okay, if all of this was Too Long Didn’t Read for you, here is the Cliff’s Notes version of what LSTCIFG’s online training is all about:

LSTCIFG coupon & course info

Course Name: Linux Security: The Complete Iptables Firewall Guide

Subtitle: Linux Security Improved. Create professional Netfilter/Iptables Firewalls. All you need to know about Netfilter/Iptables

Instructor: Taught by Andrei Dumitrescu, Crystal Mind Academy

Category: IT & Software

Subcategory: Network & Security

Provided by: Udemy

Price: $12.99 (before discount)

Free coupon code: Get Udemy coupon code discount at top of page (no charge for coupon, especially since we are compensated for referrals via affiliate marketing)

LSTCIFG review info & popularity

Prior to August 24, 2025…

Students: 3,058 students enrolled

Ratings: 470 reviews

Rank: ranked #5711 in Udemy IT & Software Courses

Rankings tip: rankings change all the time, so even if Linux Security: The Complete Iptables Firewall Guide is a bestseller or one of the top Udemy courses one year, it doesn’t mean it will be a top Udemy course the next year

LSTCIFG final details

Languages: English

Skill level: All Levels

Lectures: 98 lectures lectures lessons

Duration: 6.5 total hours hours of video

What you get: Acquire an In-Depth Understanding of Netfilter/Iptables Linux Firewall (Chains, Tables, Matches, Targets).

Target audience: Linux Sysadmins.

Requirements: Local root access to a Linux distribution like Ubuntu or CentOS. No paid software required.

Access: Lifetime access

Peace of mind: 30 day money back guarantee

Availability: available online, as well as on iOS and Android

Download options: check course to see if you can download lessons