Ultimate Guide to Tools and Techniques of Reconnaissance in Ethical Hacking

Tools and Techniques of Reconnaissance in Ethical Hacking

As hackers continually enhance their skills and employ more sophisticated techniques to breach security systems, technology also evolves in clever ways to counter these threats. This article aims to shed light on what reconnaissance entails in the context of cyberattacks, how to thwart cyber threats utilizing reconnaissance, and the necessary steps to protect against and mitigate these threats. If you’re passionate about cybersecurity and wish to delve into ethical hacking practices, considering specialized training programs like Ethical Hacking Training in Chennai can provide you with the expertise to navigate and counteract evolving cyber threats.

What is Reconnaissance?

Ethical hacking begins with gathering information and becoming familiar with the target system. Reconnaissance is a crucial initial step involving techniques like footprinting, scanning, and enumeration. Its aim is to collect as much hidden information about the target system as possible.

Reconnaissance is vital for discovering and obtaining sensitive information. It provides attackers with detailed insights necessary for penetration testing in the field of information security.

By discreetly interacting with a network’s open ports and running services, an attacker can gather valuable information without directly engaging with the network. This information can potentially facilitate unauthorised access to networks beyond the internet. Thus, reconnaissance serves as a valuable source of vulnerable information open to exploitation.

Surprisingly, the duration of a reconnaissance process to infiltrate networks remains uncertain; it could take weeks or even months. Additionally, even without gaining access to an information system, reconnaissance can still lead to a data breach by collecting sensitive data and exploiting networks. For individuals interested in understanding the intricacies of cybersecurity and learning how to counter such threats, pursuing specialized training programs like Ethical Hacking Training in Bangalore can provide valuable insights and skills to proactively address potential vulnerabilities.

An ethical hacker typically follows seven steps during reconnaissance to gather comprehensive information about a target system:

  1. Collecting initial information
  2. Determining the network’s range
  3. Identifying active machines
  4. Discovering available access points and ports
  5. Identifying the operating system by its fingerprint
  6. Locating services on ports
  7. Creating a network map

For gathering information about a network, an attacker might employ the following steps:

  • Assessing file permissions
  • Examining running network services
  • Identifying the operating system platform
  • Investigating trust relationships
  • Accessing user account information

Types of Reconnaissance

There are two primary types of reconnaissance: active reconnaissance and passive reconnaissance. The main distinction between the two lies in their approach and level of interaction with the target system.

Types of Reconnaissance

Active Reconnaissance

Active reconnaissance involves cybercriminals using tools like automated scanning and manual testing, including techniques such as ping and netcat, to gather information about computer systems. This approach generates more activity within the system and is more likely to be detected, but it is generally faster and more precise.

Port scanning

Port scanning serves as an example of active reconnaissance. It involves scanning computer ports to identify open ports through which information flows in and out of a computer system. Attackers utilise port scanning to identify visible services and potential points for initiating attacks. During port scanning, data from open ports is retrieved and analysed.

Tools and Techniques Used in Reconnaissance

Several tools and techniques are used in active reconnaissance. Here are a couple of examples:


Nmap is one of the most popular tools for active network reconnaissance. It enables users to gather information about a system and its programs. Nmap utilises various scan types that leverage the intricacies of how a system or service operates. By scanning a system or a range of IP addresses under a target’s control, an attacker can acquire extensive knowledge about a network.


Primarily designed as an exploitation toolkit, Metasploit contains multiple prepackaged exploits for various vulnerabilities. It offers insights into a wide range of vulnerable machines, even for those new to hacking.

Although Metasploit is primarily intended for exploitation, it can also be utilized for reconnaissance. By using the auto pawn feature in Metasploit, a hacker can make use of any means available to attempt to exploit a target. Moreover, Metasploit can be employed for more nuanced reconnaissance, allowing for more targeted analysis.

Passive Reconnaissance

Passive reconnaissance methods involve the use of tools such as Wireshark and Shodan to collect information without direct interaction with systems. OS fingerprinting is also used to extract information.

By employing passive reconnaissance, data can be gathered without directly engaging with the system or application under investigation. Information is collected through web searches and free reports. The target system is unlikely to detect the IP address during passive reconnaissance.

Passive reconnaissance can be conducted without direct interaction with the target, ensuring that no requests are sent to the target system. This way, the target system remains unaware that information is being gathered about it. Typically, passive information gathering relies on public resources that store information about the target.

Open-source intelligence (OSINT) involves gathering information from publicly available resources. This approach can yield various data, including IP addresses, domain names, email addresses, names, hostnames, DNS records, and even details about the software running on a website and its associated CVEs (Common Vulnerabilities and Exposures).

Tools and Techniques Used


Wireshark is renowned for its network traffic analysis capabilities, but it is also highly valuable for passive network reconnaissance. If a hacker gains access to a company’s Wi-Fi network or monitors employee network traffic, they can analyse this traffic using Wireshark to obtain crucial insights about the network. Here’s a more detailed explanation of its capabilities and potential risks:

Network Traffic Analysis

Wireshark enables users to capture and analyse network packets, providing detailed insights into the communication protocols and data exchanged between devices on a network.

It helps network administrators and security professionals troubleshoot network issues, analyse performance, and detect potential security threats.

Passive Network Reconnaissance

In the context of malicious activities, if a hacker gains unauthorised access to a company’s Wi-Fi network or intercepts employee network traffic, they can use Wireshark to capture and analyse the data packets exchanged over the network.

Through network traffic analysis, hackers can potentially identify sensitive information, such as login credentials, unencrypted data, or other confidential information transmitted over the network.

Potential Risks and Security Concerns

Unauthorised use of Wireshark for capturing and analysing network traffic can pose serious security risks, as it allows malicious actors to intercept and monitor sensitive data without the knowledge or consent of the network owners or users.

Hackers can exploit the information obtained through Wireshark to launch further attacks, compromise security measures, or gain unauthorised access to critical systems and data.

To mitigate the risks associated with unauthorised network traffic analysis, organisations should implement robust security measures, including:

Implementing strong encryption protocols to protect sensitive data transmitted over the network.

Monitoring network traffic for any suspicious or unusual activities that may indicate unauthorised access or data interception.

Conduct regular security audits and assessments to identify potential vulnerabilities and ensure that security protocols are up to date.

By prioritizing network security and adopting proactive measures to safeguard against potential security threats, organizations can reduce the risk of unauthorized access and data breaches through the misuse of tools like Wireshark. For individuals looking to deepen their understanding of cybersecurity and enhance their ability to protect networks, engaging in specialized training programs such as Cyber Security Training in Chennai can offer valuable knowledge and skills to mitigate potential risks effectively.


Shodan is an internet-connected device search engine. As the Internet of Things continues to grow, more and more insecure devices are being connected to the Internet.

Hackers utilize Shodan to locate devices within a company’s IP address range. Identifying one or more vulnerable IoT (Internet of Things) devices on a network can serve as an excellent starting point for a future attack, as many IoT devices are vulnerable by default.

Internet-Connected Device Search Engine

Shodan specializes in searching and indexing internet-connected devices, including IoT devices, servers, webcams, industrial control systems, and more.

It provides detailed information about these devices, including their IP addresses, open ports, services running, and potential vulnerabilities.

Risks with IoT Devices

As the number of internet-connected IoT devices continues to increase, so does the potential risk of inadequate security measures and vulnerabilities.

Many IoT devices are known to have default or weak security configurations, making them susceptible to various cyber threats and unauthorized access.

Utilization by Hackers

Hackers leverage Shodan to identify vulnerable devices within a company’s IP address range, enabling them to target and exploit these devices for malicious purposes.

Once hackers locate vulnerable IoT devices, they may attempt to compromise these devices to gain unauthorized access to the network or launch further attacks.

Starting Point for Attacks

Identifying insecure IoT devices through Shodan serves as a critical starting point for potential cyber attacks, as these devices can be exploited as entry points to compromise the broader network or launch targeted attacks.

It is crucial for organisations and individuals to prioritize the security of their IoT devices and networks by implementing robust security measures, such as regularly updating firmware, using strong authentication mechanisms, and segmenting IoT devices from critical network infrastructure. Additionally, staying informed about the latest security vulnerabilities and best practices can help mitigate the risks associated with the growing number of internet-connected devices.

OS Fingerprinting

OS fingerprinting is a technique used to determine the operating system running on a remote computer. Since most exploitable vulnerabilities are specific to particular operating systems, OS fingerprinting plays a vital role in cyber reconnaissance.


Search engines, like Google, are a powerful tool for conducting passive reconnaissance. They offer a wide range of possibilities for information gathering. Both programmers and attackers can use search engines for activities like Google hacking, where innovative hacking strategies are combined with basic investigative techniques to potentially uncover valuable information.

Passive Reconnaissance

Passive reconnaissance involves collecting information about a target without directly interacting with the target system. Search engines play a vital role in this process by indexing a vast amount of publicly available information, including website content, documents, and other online resources. Explore comprehensive Ethical Hacking Interview Questions and Answers to prepare for your next cybersecurity job interview. Gain insights into the latest techniques, tools, and ethical hacking principles to demonstrate your expertise and ace the interview process.

Google Hacking

Google hacking refers to the use of advanced search operators and techniques to uncover sensitive or valuable information that is not intended for public access.

Attackers often use Google hacking to identify vulnerable systems, exposed sensitive data, or misconfigurations that could potentially be exploited for malicious purposes.

Innovative Hacking Strategies

Google hacking involves combining innovative hacking strategies with basic investigative techniques to uncover hidden or sensitive information that might not be readily accessible through conventional search queries.

This may include using specific search queries, operators, or combinations of keywords to reveal confidential data, system vulnerabilities, or potential entry points for a cyber attack.

Information Gathering

For both programmers and attackers, search engines provide a wide array of possibilities for information gathering, which can include studying publicly available data, understanding trends, and conducting market research.

However, it’s crucial to distinguish between ethical and unethical practices, as using search engines for malicious activities can lead to serious legal and ethical consequences.

It’s essential for businesses and individuals to be aware of the potential risks associated with information exposure and to implement robust security measures to protect sensitive data from unauthorized access or exploitation. Moreover, practicing responsible and ethical use of search engines can help prevent the misuse of sensitive information and contribute to maintaining a secure online environment.


Nessus is software designed for scanning vulnerabilities in corporate networks. It focuses on identifying weak applications running within a network and provides insights into potentially exploitable weaknesses. While Nessus is a paid scanner, the information it provides is comprehensive, making it a valuable investment for hackers.

Vulnerability Scanning and Assessment

Nessus is known for its robust capabilities in scanning corporate networks to identify vulnerabilities and potential security weaknesses.

It focuses on detecting vulnerabilities in various network devices, applications, and operating systems, helping organizations to prioritize and address potential security risks.

Comprehensive Information and Insights

Nessus provides in-depth information on vulnerabilities, including their severity levels and potential impact on the network and systems.

It offers detailed reports and recommendations for remediation, enabling organizations to take proactive measures to secure their networks and prevent potential security breaches.

Paid Software with Valuable Features

While Nessus is a paid software solution, its comprehensive scanning capabilities and the depth of information it provides make it a valuable investment for organizations serious about maintaining robust cybersecurity measures.

The investment in Nessus often translates to an enhanced understanding of the network’s security posture and aids in making informed decisions for strengthening the overall security infrastructure.

Preferred Tool for Ethical Hackers

Ethical hackers and cybersecurity professionals often rely on Nessus to conduct thorough vulnerability assessments, as it provides a reliable and detailed overview of the security status of the network and its components.

While Nessus is a premium vulnerability scanner, its reputation and the depth of its features make it a preferred choice for organizations looking to conduct comprehensive and thorough vulnerability assessments to ensure the security of their networks and systems. It’s crucial for businesses to invest in reliable security solutions like Nessus to stay ahead of potential cyber threats and maintain a strong security posture. If you want to know more about the latest salary trends for ethical hackers, Check out Ethical Hacker Salary For Freshers, which will help you get an insight into the packages as per the companies, skills and experience.


OpenVAS (Open Vulnerability Assessment System) is indeed a significant open-source response to the transition of Nessus, a popular vulnerability scanner, from an open-source model to a closed-source commercial product. Here’s a further breakdown of OpenVAS and its relationship to Nessus:

Background on Nessus and OpenVAS

Nessus was initially an open-source project, but it transitioned to a proprietary, closed-source model. This transition led to the development of OpenVAS, which aimed to provide a free and open-source alternative with similar capabilities to the last open-source version of Nessus.

Functionality and Features

OpenVAS is designed to scan networks for vulnerabilities and provide a comprehensive assessment of potential security risks.

It offers functionalities such as vulnerability scanning, detection of misconfigurations, and the identification of potential weaknesses in systems and networks.

Comparison to Nessus

OpenVAS provides a viable alternative to commercial vulnerability scanners like Nessus, particularly for organisations seeking cost-effective security solutions without compromising on essential scanning capabilities.

While OpenVAS offers similar functionalities to the last open-source version of Nessus, it might lack some of the features that have been added to the commercial version of Nessus since its transition.

Community and Development

OpenVAS is backed by a strong community of developers and contributors who work on maintaining and updating the tool to ensure it remains effective and relevant in the ever-evolving landscape of cybersecurity.

OpenVAS’s open-source nature not only allows for its continued development but also encourages community contributions, making it a valuable asset for organizations looking for robust vulnerability assessment capabilities without the costs associated with commercial solutions. However, for organizations with specific requirements and the need for advanced features, the commercial version of Nessus or other commercial vulnerability assessment tools might be more suitable. If you’re interested in mastering cybersecurity tools like OpenVAS and enhancing your skills in vulnerability assessment, consider enrolling in specialized training programs such as Cyber Security Training in Pune for comprehensive learning and practical experience.

7 Fundamentals of Reconnaissance

Reconnaissance operations are guided by seven key principles:

  1. Sustain a constant reconnaissance system
  2. Avoid hoarding reconnaissance resources
  3. Align with the reconnaissance objective
  4. Provide precise and timely information
  5. Ensure adequate space for manoeuvring
  6. Engage and monitor adversary forces
  7. Quickly assess and adapt to the situation.

How to prevent a Reconnaissance Attack

Businesses can use penetration testing to see what information their network could expose during a reconnaissance attack. They can use passive scanning tools to check which devices are connected and vulnerability scanners to find weaknesses.

Penetration Testing

Penetration testing, often referred to as pen testing, is a simulated cyber-attack against a computer system, application, or network to identify vulnerabilities that attackers could exploit.

It helps businesses assess the security of their systems and infrastructure by attempting to exploit vulnerabilities in a controlled manner, thus providing insights into potential weak points.

Passive Scanning Tools

Passive scanning tools are used to gather information about devices and networks without actively engaging with the target.

These tools help in identifying the devices connected to a network and can provide valuable information for further analysis and potential security enhancements.

Vulnerability Scanners

Vulnerability scanners are automated tools that scan computer systems, networks, or applications for security weaknesses.

They help in identifying known vulnerabilities and misconfigurations, thereby allowing businesses to proactively address these issues before they are exploited by malicious actors.

Security Information and Event Management (SIEM)

SIEM solutions collect and analyse security information from various devices on a network.

They provide real-time analysis of security alerts generated by applications and network hardware, helping businesses detect and respond to security incidents more effectively.

Stateful Firewall

A stateful firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

It maintains a record of the state of active connections and can distinguish legitimate packets for different types of connections, thus providing an additional layer of security.

Implementing these security measures can significantly enhance the overall security posture of a business’s network infrastructure. It is essential for businesses to regularly assess their security practices and stay updated with the latest security technologies to defend against evolving cyber threats. Additionally, maintaining a comprehensive incident response plan can help businesses effectively mitigate and respond to potential security incidents.

Usage in Penetration Testing

Understanding a target’s digital landscape plays a pivotal role in penetration testing. This crucial initial step shapes the subsequent actions in the testing process. In this phase, passive techniques are utilised to gather data about the company, its workforce, and its technological infrastructure.

Active techniques are also employed to acquire specific information about the target’s systems, including details about the operating system, active services, and accessible ports. A proficient penetration tester combines both passive and active data collection methods to determine the most effective approach for breaching a company’s defences.

While achieving 100 percent security is not feasible, we can minimise the impact of potential breaches by implementing the highest possible level of security, thereby limiting the ability of reconnaissance to extract information about the systems.

Reconnaissance stands as a crucial phase in hacking activities, where hackers meticulously gather information about their target. This meticulous process enables hackers to identify potential attack vectors and pinpoint vulnerabilities in the target system or network. The information gathered during reconnaissance serves as a foundation for planning and executing cyber attacks. If you’re intrigued by the realm of cybersecurity and want to deepen your understanding, exploring specialized training programs, such as IOT Training in Chennai, can equip you with the skills to navigate the dynamic landscape of cybersecurity threats and defences.

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