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Port scanning or OS fingerprinting

Port scanning or OS fingerprinting

Port scanning or OS fingerprinting. Believe it or not!

The fact is pretty obvious that footprinting is essential to any successful attack. By and large, 70% of any attack should be spent gathering precise footprinting. In doing so, an attacker presumably knows operating system, open ports and any services running on those open ports as well as any vulnerable applications installed.
Certainly, all of this information will be paramount in order to determine the selection of tools and technologies.

There are two different types of footprinting or reconnaissance: active or passive. Each one has pros and cons.

Here let us walk through active footprinting which we interact directly with a target. Active type is more accurate and faster than the passive one. However, it involves more risk of detection and sometimes could get caught unless an attacker has permission in written form.

One of the first steps in any active footprinting is to reduce a set of IP ranges into a targeted and active host.

To achieve this, it does require performing port scanning or Operation system fingerprinting. There are numerous types of port scanners to name. But we will discuss a popular open-source tool called Nmap.

Nmap is a free and open source tool for network discovery and security auditing. It comes with either command line or GUI version. Nmap runs on all major operating systems such as Windows, Linux, and Mac OS X.
Before we start port scanning, we need to understand the TCP three-way Handshake.

TCP three-way Handshake

As a diagram is shown above, the host attempting a connection sends a destination host a packet with a SYN flag. Then, the remote host would check that the proper authorizations are in place for this connection to be made. If all the requirements are met, then the remote host sends the first host a packet with the SYN and ACK flags. Finally, the first host sends a single ACK flag back to the second host, completing the handshake and establishing the connection.

Basic Nmap Scanning

First, we will do basic ping scan which simply pings every IP in a range of IPs and reports any hosts that respond.
As seen below, we scan a range of IP that it will diagnose every IP from to So we can see there is a list of hosts on a network.

Based on the scan result below, we have three hosts are up running currently. (, &

OS Discovery
Next, we will identify what operating system OS the particular host running.

According to the above screenshot, we clearly see the detail information of operating system for two particular hosts.

Comphrensive Nmap Scanning

There is not only very basic scanning with Nmap but also comprehensive investigation like open or close ports and services as well as its version.

Let us examine any open ports, services, and its version.
The Nmap command with -sV option actively probe open ports to determine what service and version they are running.

When performing a version scan (-sV), Nmap sends a series of probes, each of which is assigned a rarity value between one and nine. If we look up the scanning result against, we have seen all open ports, type of services running on those ports and its version precisely.

Here is another scanning result for another host Sometimes, the open ports could ensure us the type of operating system as another alternative guess.

Port scanning or OS fingerprinting

Port scanning or OS fingerprinting

Please remember that proper footprinting is a very important fundamental for any successful attack.
There are many tools for port scanning or OS fingerprinting other than Nmap. However, Nmap always stays ahead of the rest.

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  1. John W

    October 10, 2017 at 2:57 am

    Thanks for the info! What are other tools for doing the same thing as Nmap?

    • Kasper

      October 10, 2017 at 4:13 am

      Would recommend Nessus which is a web-based application!

  2. MAUNG

    October 11, 2017 at 1:55 am

    Interesting article about hacking websites. You guys are really awesome and possess tons of knowledge.

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How to guide: Check if your Facebook Account has been hacked?


How to guide: Check if your Facebook Account has been hacked?

At the end of September, it was revealed that a Facebook security flaw allowed the access tokens of over 50 Million accounts to be stolen. Access tokens allow users to stay signed in on devices, rather than signing in every time they interact with a Facebook app. On Friday 12 October, after weeks of investigation, Facebook reported that the actual number of accounts affected was 30 million, not 50.


The investigation into how this was made possible, and the extent of the data stolen is still ongoing, but Facebook have said there is no need for users to log out or change their password. Facebook forced 90 million users to log out when the breach was discovered.


Users can use this page to check if they were one of the accounts affected in the incident, as well as read any recent findings from the investigation. When you visit page, if you are not one of the affected users it will tell you this in a statement towards the bottom of the page, and there is no further action required from you other than remaining security conscious when it comes to passwords and such. You will also see a message saying your account hasn’t been compromised if you are one of the one million users to who their tokens stolen but information remained safe.


If you fall into the other 29 million users camp, then you will see one of two messages, depending on the level of your information that was stolen. Fifteen million users had their name, email addresses and phone numbers compromised by hackers. While this is serious enough itself, the other 14 million have a more serious data breach problem.


The other 14 million have had the above information stolen, as well as their username, date of birth, devices you use, gender, language settings and possibly more data such as religious and political views. It’s also possible that they accessed your 10 most recent locations and 15 most recent searches, giving a detailed window into your online presence.


There is currently no evidence that hackers used the vulnerability to attack third-party apps and services to gather more information, which was technically possible.  Facebook also continues to report that no passwords of credit card information has been compromised. We are yet to see the full fallout from the breach, but there is also evidence that Facebook logins are being sold on the dark web.


While that data is now out there in the hands of attackers, Facebook has used their support page to offer some advice on avoiding phishing schemes. This is a good move from Facebook, but it doesn’t make up for the grievous level of the data breach and the users it has left vulnerable to tailored phishing attacks now their data is out there.

Photo by Glen Carrie on Unsplash

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How to Secure Your Linux Server

How to Secure Your Linux Server

How to Secure Your Linux Server

It’s important for anyone running a Linux server, or any type of server for that matter, secure. Especially if it communicates with the outside world. Servers are like your houses in the digital realm. They have to be kept secure from intruders. So you have a Linux server, here’s how to secure it.

  • Keep Your Server Clean and Lean

In other words, keep it simple, but secure. Install the apps and run only the services that you need. Additional apps, introduce vulnerabilities as well as unpatched services that can be exploited by external malicious actors. Keeping the server clean and lean also speeds up its performance. Also, depending on the Linux distro, a number of extra services will be run by default. Keep an eye out for those services. Check if they’re really important and if they are, make sure they’re updated.

A simple netstat –npl command in the terminal will show you all the running services and the ports they use. That’s another thing. These services might be using some ports you want to keep closed. Disable unwanted services with the following command.

Systemctl disable service_name


  • Do not Log in as Root

It’s no secret that logging in as Root user gives you unrestricted access to everything in your Linux setup. And for many Linux users, it’s the easiest way to use Linux which is why most newbies log in as Root. Malicious attackers know this too. When users log in as Root, any running apps and services with vulnerabilities also give attackers unlimited access to everything else. The best practice for Linux users, is to create a user with enough sudo access to perform most tasks and only switch to Root when needed.

In Ubuntu for example, you can add a new user with sudo powers by typing in the following at the terminal:

adduser usercansudo

qpasswd –a usercansudo sudo

Afterwards, log out of the system and login as the new user then disable the Root user by editing the sshd_conf file.

Nano /etc/ssh/sshd_conf

Look for this commented item: #PermitRootLogin no

Remove the comment, save the file and restart the ssh service using the following command:

systemctl restart sshd


  • Keep the Server to Yourself and others you Trust

Restrict access to your server to just you and others you implicitly trust. In the previous item, create as many users as you can with level access and disable root. The fewer the better though.

  • Port Change

When logging in remotely, the default port for ssh is 22 which is what most people, including attackers would do to get into a Linux server. This port can be changed and by changing this port, eavesdroppers, attackers and bots will be left guessing how to log in to your system. It’s simple but effective. To change the ssh port, we go back to the sshd_conf file. You can issue the following commands:

sudo nano /etc/ssh/sshd_conf


Find the commented port line:

#Port 22


Uncomment it and change the port number to something else. Feel free to change 22 to something between 1024 and 32,767 but make sure that no other service uses your chosen number. Then save the file. Restart the ssh service.

systemctl restart sshd


You can check  if it works by logging in through ssh with this command:

ssh -p{port_number}@server_IP


ssh –p1027

  • Always Keep Your Server Patched and Updated

You’ve probably read plenty of articles regarding vulnerabilities that no basic user could probably think of but continuously explored by determined hackers out for a quick buck. No server is secure, not even Linux and the best defense for this, apart from a good firewall and anti-malware programs, is to keep your operating system and its packages updated. Always be on the lookout for core or kernel updates.


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How To Become an Ethical Hacker – Beginners Guide

How To Become an Ethical Hacker - Beginners Guide- hackwarenewscom

How To Become an Ethical Hacker – Beginners Guide. I’m sure you read stories about ethical hacking, but not knowing what that means?

Our article will cover  few points for people with no experience in cybersecurity or have limited experience.

We receive many emails asking on how to become ethical hacker. Some of more frequent questions “where should I start?”. We will try to answer these questions and give you a more technical details on how to start a career in cybersecurity as a beginner and how to gain more expertise in the domain.

Remember if your goal is to learn hacking for the reason of hacking into your friend’s Facebook account or email, it will not work for you. But if you decided to learn hacking because of your passion for technology and willingness to be an expert in computer systems, things should workout for you!

Career in cybersecurity is more like saying career in Banking. There will be so many niches within the industry from auditing, pentesting, social engineering, digital foresnics, malware / software detecting, etc. You many choose any of the above, however in this article we will cover generic skills that you need before starting your career.

If your background doesn’t bring any experience to the table, don’t worry, we all been there. Nobody has all the necessary skill from beginning. So our advice in your case is to learn absolute fundamentals.


  • What is hacking?

Hacking is determining weakness and vulnerabilities of systems and attain access to it.

Ethical hacker have an official and legitimate permission to do a security assessment of a system, but hacker is doing this unauthorized.

Here are some type of hackers for your intro:

Hacktivist – those who hack due to some ideas and to make a statement.

Script kiddie –  they usually use pre-build tools and have no technical skills.

Grey hat  – they reveal the weakens to the company after they get unauthorized access.

Black hat – get unauthorized access

White hat – ethical hacker, they document everything they do and reveal the weaknesses & vulnerabilities to the company.


  • What skills required for ethical hacker

– Programming skills

– Fundamentals of Networking

– Operating System

– Get to know as many technology as you can put your hands on


  • What to code in ?

To answer this question, one have to consider on what platform you will be working on.

– Web applications: PHP, ASP , JPS

– Mobile apps : Swift/Objective-C, Java( Android) ,

Software [desktop] : C#, C++, Objective-C

It is necessary to learn the fundamentals of programming, like data types, the variable manipulation at the OS level to the use of functions, etc. Here are some tips to take in consideration:

  1. Try to understand the OS level operations on the language you are learning or alternatively learn the assembly language.
  2. Keep your self motivated in your learning path and remember to achieve results takes time.


  • Here are resources that will help to learn from scratch
  1. Breaking into Information Security: Learning the Ropes 101
  2. Web Hacking 101


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