Hacker Types
Overview
Hackers can be classified into different categories such as white hat, black hat, and grey hat, based on their intent of hacking a system. These different terms come from old Spaghetti Westerns, where the bad guy wears a black cowboy hat and the good guy wears a white hat.
White Hat Hackers
White Hat hackers are also known as Ethical Hackers. They never intent to harm a system, rather they try to find out weaknesses in a computer or a network system as a part of penetration testing and vulnerability assessments.

Ethical hacking is not illegal and it is one of the demanding jobs available in the IT industry. There are numerous companies that hire ethical hackers for penetration testing and vulnerability assessments.

Black Hat Hackers
Black Hat hackers, also known as crackers, are those who hack in order to gain unauthorized access to a system and harm its operations or steal sensitive information.

Black Hat hacking is always illegal because of its bad intent which includes stealing corporate data, violating privacy, damaging the system, blocking network communication, etc.

Grey Hat Hackers
Grey hat hackers are a blend of both black hat and white hat hackers. They act without malicious intent but for their fun, they exploit a security weakness in a computer system or network without the owner’s permission or knowledge.

Their intent is to bring the weakness to the attention of the owners and getting appreciation or a little bounty from the owners.

Miscellaneous Hackers
Apart from the above well-known classes of hackers, we have the following categories of hackers based on what they hack and how they do it −

Red Hat Hackers

Red hat hackers are again a blend of both black hat and white hat hackers. They are usually on the level of hacking government agencies, top-secret information hubs, and generally anything that falls under the category of sensitive information.

Blue Hat Hackers

A blue hat hacker is someone outside computer security consulting firms who is used to bug-test a system prior to its launch. They look for loopholes that can be exploited and try to close these gaps. Microsoft also uses the term BlueHat to represent a series of security briefing events.

Elite Hackers

This is a social status among hackers, which is used to describe the most skilled. Newly discovered exploits will circulate among these hackers.

Script Kiddie

A script kiddie is a non-expert who breaks into computer systems by using pre-packaged automated tools written by others, usually with little understanding of the underlying concept, hence the term Kiddie.

Neophyte

A neophyte, “n00b”, or “newbie” or “Green Hat Hacker” is someone who is new to hacking or phreaking and has almost no knowledge or experience of the workings of technology and hacking.

Hacktivist

A hacktivist is a hacker who utilizes technology to announce a social, ideological, religious, or political message. In general, most hacktivism involves website defacement or denialof-service attacks.

Overview
Hacking has been a part of computing for almost five decades and it is a very broad discipline, which covers a wide range of topics. The first known event of hacking had taken place in 1960 at MIT and at the same time, the term “Hacker” was originated.
Hacking is the act of finding the possible entry points that exist in a computer system or a computer network and finally entering into them. Hacking is usually done to gain unauthorized access to a computer system or a computer network, either to harm the systems or to steal sensitive information available on the computer.

Hacking is usually legal as long as it is being done to find weaknesses in a computer or network system for testing purpose. This sort of hacking is what we call Ethical Hacking.

A computer expert who does the act of hacking is called a “Hacker”. Hackers are those who seek knowledge, to understand how systems operate, how they are designed, and then attempt to play with these systems.

Types of Hacking
We can segregate hacking into different categories, based on what is being hacked. Here is a set of examples −

Website Hacking − Hacking a website means taking unauthorized control over a web server and its associated software such as databases and other interfaces.

Network Hacking − Hacking a network means gathering information about a network by using tools like Telnet, NS lookup, Ping, Tracert, Netstat, etc. with the intent to harm the network system and hamper its operation.

Email Hacking − It includes getting unauthorized access on an Email account and using it without taking the consent of its owner.

Ethical Hacking − Ethical hacking involves finding weaknesses in a computer or network system for testing purpose and finally getting them fixed.

Password Hacking − This is the process of recovering secret passwords from data that has been stored in or transmitted by a computer system.

Computer Hacking − This is the process of stealing computer ID and password by applying hacking methods and getting unauthorized access to a computer system.

Advantages of Hacking
Hacking is quite useful in the following scenarios −

To recover lost information, especially in case you lost your password.

To perform penetration testing to strengthen computer and network security.

To put adequate preventative measures in place to prevent security breaches.

To have a computer system that prevents malicious hackers from gaining access.

Disadvantages of Hacking
Hacking is quite dangerous if it is done with harmful intent. It can cause −

Massive security breach.

Unauthorized system access on private information.

Privacy violation.

Hampering system operation.

Denial of service attacks.

Malicious attack on the system.

Purpose of Hacking
There could be various positive and negative intentions behind performing hacking activities. Here is a list of some probable reasons why people indulge in hacking activities −

Just for fun

Show-off

Steal important information

Damaging the system

Hampering privacy

Money extortion

System security testing

To break policy compliance

Famous Hackers
In this chapter, we will have a brief synopsis of some of the famous Hackers and how they became famous.
Jonathan James

Jonathan James was an American hacker, illfamous as the first juvenile sent to prison for cybercrime in United States. He committed suicide in 2008 of a self-inflicted gunshot wound.

In 1999, at the age of 16, he gained access to several computers by breaking the password of a server that belonged to NASA and stole the source code of the International Space Station among other sensitive information.

Ian Murphy

Ian Murphy, also known as Captain Zap, at one point of time was having high school students steal computer equipment for him. Ian selfproclaims to have been “the first hacker ever convicted of a crime”.

Ian’s career as a master hacker was fabricated in 1986 after he and his unemployed wife decided to form some type of business.

He has a long history of computer and Internet frauds. One of his favourite games is to forge Email headers and to send out third-party threat letters.

Kevin Mitnick

Kevin Mitnick is a computer security consultant and author, who infiltrates his clients’ companies to expose their security strengths, weaknesses, and potential loopholes.

He is the first hacker to have his face immortalized on an FBI “Most Wanted” poster. He was formerly the most wanted computer criminal in the history of United States.

From the 1970s up until his last arrest in 1995, he skilfully bypassed corporate security safeguards, and found his way into some of the most well-guarded systems such as Sun Microsystems, Digital Equipment Corporation, Motorola, Netcom, and Nokia.

Mark Abene

Mark Abene, known around the world by his pseudonym Phiber Optik, is an information security expert and entrepreneur. He was a high-profile hacker in the 1980s and early 1990s. He was one of the first hackers to openly debate and defend the positive merits of ethical hacking as a beneficial tool to industry.

His expertise spreads across penetration studies, on-site security assessments, secure code reviews, security policy review and generation, systems and network architecture, systems administration and network management, among many others. His clientele includes American Express, UBS, First USA, Ernst & Young, KPMG and others.

Johan Helsinguis

Johan Helsingius, better known as Julf, came into the limelight in the 1980s when he started operating the world’s most popular anonymous remailer, called penet.fi.

Johan was also responsible for product development for the first Pan-European internet service provider, Eunet International.

He is at present, a member of the board of Technologia Incognita, a hackerspace association in Amsterdam, and supports the communication companies worldwide with his cyber knowledge.

Linus Torvalds

Linus Torvalds is known as one of the best hackers of all time. He rose to fame by creating Linux, the very popular Unix-based operating system. Linux is open source and thousands of developers have contributed to its Kernel. However, Torvalds remains the ultimate authority on what new code is incorporated into the standard Linux kernel. As of 2006, approximately two percent of the Linux kernel was written by Torvalds himself.

He just aspires to be simple and have fun by making the world’s best operating system. Torvalds has received honorary doctorates from Stockholm University and University of Helsinki.

Robert Morris

Robert Morris, known as the creator of the Morris Worm, the first computer worm to be unleashed on the Internet. The worm had the capability to slow down computers and make them no longer usable. As a result of this, he was sentenced to three years’ probation, 400 hours of community service and also had to pay a penalty amount of $10,500.

Morris is currently working as a tenured professor at the MIT Computer Science and Artificial Intelligence Laboratory.

Gary McKinnon

Gary McKinnon is a renowned systems administrator and hacker. He was famously accused of the “biggest military computer hack of all time”. He had successfully hacked the networks of Army, Air Force, Navy and NASA systems of the United States government.

In his statements to the media, he has often mentioned that his motivation was only to find evidence of UFOs, antigravity technology, and the suppression of “free energy” that could potentially be useful to the public.

Kevin Poulsen

Kevin Poulsen, also known as Dark Dante, became famous for his notoriety when he took over all the telephone lines of Los Angeles radio station KIIS-FM, guaranteeing that he would be the 102nd caller and win the prize of a Porsche 944 S2.

Poulsen also drew the ire of FBI, when he hacked into federal computers for wiretap information, for which he had to serve a sentence of five years. He has reinvented himself as a journalist and has carved a niche for himself in this field.

Terminologies
Following is a list of important terms used in the field of hacking.
Adware − Adware is software designed to force pre-chosen ads to display on your system.

Attack − An attack is an action that is done on a system to get its access and extract sensitive data.

Back door − A back door, or trap door, is a hidden entry to a computing device or software that bypasses security measures, such as logins and password protections.

Bot − A bot is a program that automates an action so that it can be done repeatedly at a much higher rate for a more sustained period than a human operator could do it. For example, sending HTTP, FTP or Telnet at a higher rate or calling script to create objects at a higher rate.

Botnet − A botnet, also known as zombie army, is a group of computers controlled without their owners’ knowledge. Botnets are used to send spam or make denial of service attacks.

Brute force attack − A brute force attack is an automated and the simplest kind of method to gain access to a system or website. It tries different combination of usernames and passwords, over and over again, until it gets in.

Buffer Overflow − Buffer Overflow is a flaw that occurs when more data is written to a block of memory, or buffer, than the buffer is allocated to hold.

Clone phishing − Clone phishing is the modification of an existing, legitimate email with a false link to trick the recipient into providing personal information.

Cracker − A cracker is one who modifies the software to access the features which are considered undesirable by the person cracking the software, especially copy protection features.

Denial of service attack (DoS) − A denial of service (DoS) attack is a malicious attempt to make a server or a network resource unavailable to users, usually by temporarily interrupting or suspending the services of a host connected to the Internet.

DDoS − Distributed denial of service attack.

Exploit Kit − An exploit kit is software system designed to run on web servers, with the purpose of identifying software vulnerabilities in client machines communicating with it and exploiting discovered vulnerabilities to upload and execute malicious code on the client.

Exploit − Exploit is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a bug or vulnerability to compromise the security of a computer or network system.

Firewall − A firewall is a filter designed to keep unwanted intruders outside a computer system or network while allowing safe communication between systems and users on the inside of the firewall.

Keystroke logging − Keystroke logging is the process of tracking the keys which are pressed on a computer (and which touchscreen points are used). It is simply the map of a computer/human interface. It is used by gray and black hat hackers to record login IDs and passwords. Keyloggers are usually secreted onto a device using a Trojan delivered by a phishing email.

Logic bomb − A virus secreted into a system that triggers a malicious action when certain conditions are met. The most common version is the time bomb.

Malware − Malware is an umbrella term used to refer to a variety of forms of hostile or intrusive software, including computer viruses, worms, Trojan horses, ransomware, spyware, adware, scareware, and other malicious programs.

Master Program − A master program is the program a black hat hacker uses to remotely transmit commands to infected zombie drones, normally to carry out Denial of Service attacks or spam attacks.

Phishing − Phishing is an e-mail fraud method in which the perpetrator sends out legitimate-looking emails, in an attempt to gather personal and financial information from recipients.

Phreaker − Phreakers are considered the original computer hackers and they are those who break into the telephone network illegally, typically to make free longdistance phone calls or to tap phone lines.

Rootkit − Rootkit is a stealthy type of software, typically malicious, designed to hide the existence of certain processes or programs from normal methods of detection and enable continued privileged access to a computer.

Shrink Wrap code − A Shrink Wrap code attack is an act of exploiting holes in unpatched or poorly configured software.

Social engineering − Social engineering implies deceiving someone with the purpose of acquiring sensitive and personal information, like credit card details or user names and passwords.

Spam − A Spam is simply an unsolicited email, also known as junk email, sent to a large number of recipients without their consent.

Spoofing − Spoofing is a technique used to gain unauthorized access to computers, whereby the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host.

Spyware − Spyware is software that aims to gather information about a person or organization without their knowledge and that may send such information to another entity without the consumer’s consent, or that asserts control over a computer without the consumer’s knowledge.

SQL Injection − SQL injection is an SQL code injection technique, used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker).

Threat − A threat is a possible danger that can exploit an existing bug or vulnerability to compromise the security of a computer or network system.

Trojan − A Trojan, or Trojan Horse, is a malicious program disguised to look like a valid program, making it difficult to distinguish from programs that are supposed to be there designed with an intention to destroy files, alter information, steal passwords or other information.

Virus − A virus is a malicious program or a piece of code which is capable of copying itself and typically has a detrimental effect, such as corrupting the system or destroying data.

Vulnerability − A vulnerability is a weakness which allows a hacker to compromise the security of a computer or network system.

Worms − A worm is a self-replicating virus that does not alter files but resides in active memory and duplicates itself.

Cross-site Scripting − Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications. XSS enables attackers to inject client-side script into web pages viewed by other users.

Zombie Drone − A Zombie Drone is defined as a hi-jacked computer that is being used anonymously as a soldier or ‘drone’ for malicious activity, for example, distributing unwanted spam e-mails.

Tools
In this chapter, we will discuss in brief some of famous tools that are widely used to prevent hacking and getting unauthorized access to a computer or network system.
NMAP
Nmap stands for Network Mapper. It is an open source tool that is used widely for network discovery and security auditing. Nmap was originally designed to scan large networks, but it can work equally well for single hosts. Network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime.

Nmap uses raw IP packets to determine −

what hosts are available on the network,

what services those hosts are offering,

what operating systems they are running on,

what type of firewalls are in use, and other such characteristics.

Nmap runs on all major computer operating systems such as Windows, Mac OS X, and Linux.

Metasploit
Metasploit is one of the most powerful exploit tools. It’s a product of Rapid7 and most of its resources can be found at: www.metasploit.com. It comes in two versions − commercial and free edition. Matasploit can be used with command prompt or with Web UI.

With Metasploit, you can perform the following operations −

Conduct basic penetration tests on small networks

Run spot checks on the exploitability of vulnerabilities

Discover the network or import scan data

Browse exploit modules and run individual exploits on hosts

Burp Suit
Burp Suite is a popular platform that is widely used for performing security testing of web applications. It has various tools that work in collaboration to support the entire testing process, from initial mapping and analysis of an application’s attack surface, through to finding and exploiting security vulnerabilities.

Burp is easy to use and provides the administrators full control to combine advanced manual techniques with automation for efficient testing. Burp can be easily configured and it contains features to assist even the most experienced testers with their work.

Angry IP Scanner
Angry IP scanner is a lightweight, cross-platform IP address and port scanner. It can scan IP addresses in any range. It can be freely copied and used anywhere. In order to increase the scanning speed, it uses multithreaded approach, wherein a separate scanning thread is created for each scanned IP address.

Angry IP Scanner simply pings each IP address to check if it’s alive, and then, it resolves its hostname, determines the MAC address, scans ports, etc. The amount of gathered data about each host can be saved to TXT, XML, CSV, or IP-Port list files. With help of plugins, Angry IP Scanner can gather any information about scanned IPs.

Cain & Abel
Cain & Abel is a password recovery tool for Microsoft Operating Systems. It helps in easy recovery of various kinds of passwords by employing any of the following methods −

sniffing the network,

cracking encrypted passwords using Dictionary, Brute-Force and Cryptanalysis attacks,

recording VoIP conversations,

decoding scrambled passwords,

recovering wireless network keys,

revealing password boxes,

uncovering cached passwords and analyzing routing protocols.

Cain & Abel is a useful tool for security consultants, professional penetration testers and everyone else who plans to use it for ethical reasons.

Ettercap
Ettercap stands for Ethernet Capture. It is a network security tool for Man-in-the-Middle attacks. It features sniffing of live connections, content filtering on the fly and many other interesting tricks. Ettercap has inbuilt features for network and host analysis. It supports active and passive dissection of many protocols.

You can run Ettercap on all the popular operating systems such as Windows, Linux, and Mac OS X.

EtherPeek
EtherPeek is a wonderful tool that simplifies network analysis in a multiprotocol heterogeneous network environment. EtherPeek is a small tool (less than 2 MB) that can be easily installed in a matter of few minutes.

EtherPeek proactively sniffs traffic packets on a network. By default, EtherPeek supports protocols such as AppleTalk, IP, IP Address Resolution Protocol (ARP), NetWare, TCP, UDP, NetBEUI, and NBT packets.

SuperScan
SuperScan is a powerful tool for network administrators to scan TCP ports and resolve hostnames. It has a user friendly interface that you can use to −

Perform ping scans and port scans using any IP range.

Scan any port range from a built-in list or any given range.

View responses from connected hosts.

Modify the port list and port descriptions using the built in editor.

Merge port lists to build new ones.

Connect to any discovered open port.

Assign a custom helper application to any port.

QualysGuard
QualysGuard is an integrated suite of tools that can be utilized to simplify security operations and lower the cost of compliance. It delivers critical security intelligence on demand and automates the full spectrum of auditing, compliance and protection for IT systems and web applications.

QualysGuard includes a set of tools that can monitor, detect, and protect your global network.

WebInspect
WebInspect is a web application security assessment tool that helps identify known and unknown vulnerabilities within the Web application layer.

It can also help check that a Web server is configured properly, and attempts common web attacks such as parameter injection, cross-site scripting, directory traversal, and more.

LC4
LC4 was formerly known as L0phtCrack. It is a password auditing and recovery application. It is used to test password strength and sometimes to recover lost Microsoft Windows passwords, by using dictionary, brute-force, and hybrid attacks.

LC4 recovers Windows user account passwords to streamline migration of users to another authentication system or to access accounts whose passwords are lost.

LANguard Network Security Scanner
LANguard Network Scanner monitors a network by scanning connected machines and providing information about each node. You can obtain information about each individual operating system.

It can also detect registry issues and have a report set up in HTML format. For each computer, you can list the netbios name table, current logged-on user, and Mac address.

Network Stumbler
Network stumbler is a WiFi scanner and monitoring tool for Windows. It allows network professionals to detect WLANs. It is widely used by networking enthusiasts and hackers because it helps you find non-broadcasting wireless networks.

Network Stumbler can be used to verify if a network is well configured, its signal strength or coverage, and detect interference between one or more wireless networks. It can also be used to non-authorized connections.

ToneLoc
ToneLoc stands for Tone Locator. It was a popular war dialling computer program written for MS-DOS in the early 90’s. War dialling is a technique of using a modem to automatically scan a list of telephone numbers, usually dialling every number in a local area code.

Malicious hackers use the resulting lists in breaching computer security – for guessing user accounts, or locating modems that might provide an entry-point into computer or other electronic systems.

It can be used by security personnel to detect unauthorized devices on a company’s telephone network.

Skills
As an ethical hacker, you will need to understand various hacking techniques such as −
Password guessing and cracking
Session hijacking
Session spoofing
Network traffic sniffing
Denial of Service attacks
Exploiting buffer overflow vulnerabilities
SQL injection
In this chapter, we will discuss some of the skills that you would require to become an expert in Ethical Hacking.

Basic Skills
Computer Hacking is a Science as well as an Art. Like any other expertise, you need to put a lot of effort in order to acquire knowledge and become an expert hacker. Once you are on the track, you would need more effort to keep up-to-date with latest technologies, new vulnerabilities and exploitation techniques.

An ethical hacker must be a computer systems expert and needs to have very strong programming and computer networking skills.

An ethical hacker needs to have a lot of patience, persistence, and perseverance to try again and again and wait for the required result.

Additionally, an ethical hacker should be smart enough to understand the situation and other users’ mind-set in order to apply social engineering exploits. A good ethical hacker has great problem-solving skills too.

Courses & Certifications
This tutorial provides the basic guidelines to become a successful Ethical Hacker. If you want to excel in this field, then you might choose to pursue the following courses and certifications −

Obtain a bachelor’s degree in Computer Science or A+ Certificate to gain an understanding of the most common hardware and software technologies.

Get into a programmer’s role for a few years and then switch to get a tech support position.

Proceed to get network certifications like Network+ or CCNA and then security certifications like Security+, CISSP, or TICSA.

It is recommended that you get some work experience as a Network Engineer and System Administrator to understand networks and systems inside out.

Keep going through various books, tutorials and papers to understand various computer security aspects and take them as a challenge to secure your network and computer systems as network security engineer.

Study courses which cover creating Trojan horses, backdoors, viruses, and worms, denial of service (DoS) attacks, SQL injection, buffer overflow, session hijacking, and system hacking.

Master the art of penetration testing, footprinting and reconnaissance, and social engineering.

Finally go for a Certified Ethical Hacker (CEH) Certification.

GIAC (Global Information Assurance Certification) and Offensive Security Certified Professional (OSCP) are additional IT security certifications which will add a lot of value to your profile.

Final Note

You need to stay as a White Hat Hacker which means you need to work within given boundaries. Never intrude or attack any computer or network without a required permission from the authorities.

As a final note, it is highly recommended that you refrain from engaging yourself in black hat hacking which may spoil your entire career.

Process
Like all good projects, ethical hacking too has a set of distinct phases. It helps hackers to make a structured ethical hacking attack.
Different security training manuals explain the process of ethical hacking in different ways, but for me as a Certified Ethical Hacker, the entire process can be categorized into the following six phases.


Reconnaissance
Reconnaissance is the phase where the attacker gathers information about a target using active or passive means. The tools that are widely used in this process are NMAP, Hping, Maltego, and Google Dorks.

Scanning
In this process, the attacker begins to actively probe a target machine or network for vulnerabilities that can be exploited. The tools used in this process are Nessus, Nexpose, and NMAP.

Gaining Access
In this process, the vulnerability is located and you attempt to exploit it in order to enter into the system. The primary tool that is used in this process is Metasploit.

Maintaining Access
It is the process where the hacker has already gained access into a system. After gaining access, the hacker installs some backdoors in order to enter into the system when he needs access in this owned system in future. Metasploit is the preferred tool in this process.

Clearing Tracks
This process is actually an unethical activity. It has to do with the deletion of logs of all the activities that take place during the hacking process.

Reporting
Reporting is the last step of finishing the ethical hacking process. Here the Ethical Hacker compiles a report with his findings and the job that was done such as the tools used, the success rate, vulnerabilities found, and the exploit processes.

Quick Tip
The processes are not standard. You can adopt a set of different processes and tools according to your techniques that you are comfortable with. The process is of least significance as long as you are able to get the desired results.

Reconnaissance
Information Gathering and getting to know the target systems is the first process in ethical hacking. Reconnaissance is a set of processes and techniques (Footprinting, Scanning & Enumeration) used to covertly discover and collect information about a target system.
During reconnaissance, an ethical hacker attempts to gather as much information about a target system as possible, following the seven steps listed below −

Gather initial information
Determine the network range
Identify active machines
Discover open ports and access points
Fingerprint the operating system
Uncover services on ports
Map the network
We will discuss in detail all these steps in the subsequent chapters of this tutorial. Reconnaissance takes place in two parts − Active Reconnaissance and Passive Reconnaissance.

Active Reconnaissance
In this process, you will directly interact with the computer system to gain information. This information can be relevant and accurate. But there is a risk of getting detected if you are planning active reconnaissance without permission. If you are detected, then system admin can take severe action against you and trail your subsequent activities.

Passive Reconnaissance
In this process, you will not be directly connected to a computer system. This process is used to gather essential information without ever interacting with the target systems.

Footprinting
Footprinting is a part of reconnaissance process which is used for gathering possible information about a target computer system or network. Footprinting could be both passive and active. Reviewing a company’s website is an example of passive footprinting, whereas attempting to gain access to sensitive information through social engineering is an example of active information gathering.
Footprinting is basically the first step where hacker gathers as much information as possible to find ways to intrude into a target system or at least decide what type of attacks will be more suitable for the target.

During this phase, a hacker can collect the following information −

Domain name
IP Addresses
Namespaces
Employee information
Phone numbers
E-mails
Job Information
In the following section, we will discuss how to extract the basic and easily accessible information about any computer system or network that is linked to the Internet.

Domain Name Information
You can use http://www.whois.com/whois website to get detailed information about a domain name information including its owner, its registrar, date of registration, expiry, name server, owner’s contact information, etc.


Here is a sample record of www.tutorialspoint.com extracted from WHOIS Lookup −


Quick Fix

It’s always recommended to keep your domain name profile a private one which should hide the above-mentioned information from potential hackers.

Finding IP Address
You can use ping command at your prompt. This command is available on Windows as well as on Linux OS. Following is the example to find out the IP address of tutorialspoint.com

$ping tutorialspoint.com
It will produce the following result −

PING tutorialspoint.com (66.135.33.172) 56(84) bytes of data.64 bytes from 66.135.33.172: icmp_seq = 1 ttl = 64 time = 0.028 ms64 bytes from 66.135.33.172: icmp_seq = 2 ttl = 64 time = 0.021 ms64 bytes from 66.135.33.172: icmp_seq = 3 ttl = 64 time = 0.021 ms64 bytes from 66.135.33.172: icmp_seq = 4 ttl = 64 time = 0.021 ms
Finding Hosting Company
Once you have the website address, you can get further detail by using ip2location.com website. Following is the example to find out the details of an IP address −


Here the ISP row gives you the detail about the hosting company because IP addresses are usually provided by hosting companies only.

Quick Fix

If a computer system or network is linked with the Internet directly, then you cannot hide the IP address and the related information such as the hosting company, its location, ISP, etc. If you have a server containing very sensitive data, then it is recommended to keep it behind a secure proxy so that hackers cannot get the exact details of your actual server. This way, it will be difficult for any potential hacker to reach your server directly.

Another effective way of hiding your system IP and ultimately all the associated information is to go through a Virtual Private Network (VPN). If you configure a VPN, then the whole traffic routes through the VPN network, so your true IP address assigned by your ISP is always hidden.

IP Address Ranges
Small sites may have a single IP address associated with them, but larger websites usually have multiple IP addresses serving different domains and sub-domains.

You can obtain a range of IP addresses assigned to a particular company using American Registry for Internet Numbers (ARIN).


You can enter company name in the highlighted search box to find out a list of all the assigned IP addresses to that company.

History of the Website
It is very easy to get a complete history of any website using www.archive.org.


You can enter a domain name in the search box to find out how the website was looking at a given point of time and what were the pages available on the website on different dates.


Quick Fix

Though there are some advantages of keeping your website in an archive database, but if you do not like anybody to see how your website progressed through different stages, then you can request archive.org to delete the history of your website.

Fingerprinting
The term OS fingerprinting in Ethical Hacking refers to any method used to determine what operating system is running on a remote computer. This could be −
Active Fingerprinting − Active fingerprinting is accomplished by sending specially crafted packets to a target machine and then noting down its response and analyzing the gathered information to determine the target OS. In the following section, we have given an example to explain how you can use NMAP tool to detect the OS of a target domain.

Passive Fingerprinting − Passive fingerprinting is based on sniffer traces from the remote system. Based on the sniffer traces (such as Wireshark) of the packets, you can determine the operating system of the remote host.

We have the following four important elements that we will look at to determine the operating system −

TTL − What the operating system sets the Time-To-Live  on the outbound packet.

Window Size − What the operating system sets the Window Size at.

DF − Does the operating system set the Don’t Fragment bit.

TOS − Does the operating system set the Type of Service, and if so, at what.

By analyzing these factors of a packet, you may be able to determine the remote operating system. This system is not 100% accurate, and works better for some operating systems than others.

Basic Steps
Before attacking a system, it is required that you know what operating system is hosting a website. Once a target OS is known, then it becomes easy to determine which vulnerabilities might be present to exploit the target system.

Below is a simple nmap command which can be used to identify the operating system serving a website and all the opened ports associated with the domain name, i.e., the IP address.

$nmap -O -v tutorialspoint.com
It will show you the following sensitive information about the given domain name or IP address −

Starting Nmap 5.51 ( http://nmap.org ) at 2015-10-04 09:57 CDTInitiating Parallel DNS resolution of 1 host. at 09:57Completed Parallel DNS resolution of 1 host. at 09:57, 0.00s elapsedInitiating SYN Stealth Scan at 09:57Scanning tutorialspoint.com (66.135.33.172) [1000 ports]Discovered open port 22/tcp on 66.135.33.172Discovered open port 3306/tcp on 66.135.33.172Discovered open port 80/tcp on 66.135.33.172Discovered open port 443/tcp on 66.135.33.172Completed SYN Stealth Scan at 09:57, 0.04s elapsed (1000 total ports)Initiating OS detection (try #1) against tutorialspoint.com (66.135.33.172)Retrying OS detection (try #2) against tutorialspoint.com(66.135.33.172)Retrying OS detection (try #3) against tutorialspoint.com (66.135.33.172)Retrying OS detection (try #4) against tutorialspoint.com (66.135.33.172)Retrying OS detection (try #5) against tutorialspoint.com (66.135.33.172)Nmap scan report for tutorialspoint.com (66.135.33.172)Host is up (0.000038s latency).Not shown: 996 closed portsPORT STATE SERVICE22/tcp open ssh80/tcp open http443/tcp open https3306/tcp open mysqlTCP/IP fingerprint:OS:SCAN(V=5.51%D=10/4%OT=22%CT=1%CU=40379%PV=N%DS=0%DC=L%G=Y%TM=56113E6D%P=OS:x86_64-redhat-linux-gnu)SEQ(SP=106%GCD=1%ISR=109%TI=Z%CI=Z%II=I%TS=A)OPSOS:(O1=MFFD7ST11NW7%O2=MFFD7ST11NW7%O3=MFFD7NNT11NW7%O4=MFFD7ST11NW7%O5=MFFOS:D7ST11NW7%O6=MFFD7ST11)WIN(W1=FFCB%W2=FFCB%W3=FFCB%W4=FFCB%W5=FFCB%W6=FFOS:CB)ECN(R=Y%DF=Y%T=40%W=FFD7%O=MFFD7NNSNW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%AOS:=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%OS:Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=OS:A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=OS:Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%OS:T=40%CD=S)
If you do not have nmap command installed on your Linux system, then you can install it using the following yum command −

$yum install nmap
You can go through nmap command in detail to check and understand the different features associated with a system and secure it against malicious attacks.

Quick Fix

You can hide your main system behind a secure proxy server or a VPN so that your complete identity is safe and ultimately your main system remains safe.

Port Scanning
We have just seen information given by nmap command. This command lists down all the open ports on a given server.

PORT STATE SERVICE22/tcp open ssh80/tcp open http443/tcp open https3306/tcp open mysql
You can also check if a particular port is opened or not using the following command −

$nmap -sT -p 443 tutorialspoint.com
It will produce the following result −

Starting Nmap 5.51 ( http://nmap.org ) at 2015-10-04 10:19 CDTNmap scan report for tutorialspoint.com (66.135.33.172)Host is up (0.000067s latency).PORT STATE SERVICE443/tcp open httpsNmap done: 1 IP address (1 host up) scanned in 0.04 seconds
Once a hacker knows about open ports, then he can plan different attack techniques through the open ports.

Quick Fix

It is always recommended to check and close all the unwanted ports to safeguard the system from malicious attacks.

Ping Sweep
A ping sweep is a network scanning technique that you can use to determine which IP address from a range of IP addresses map to live hosts. Ping Sweep is also known as ICMP sweep.

You can use fping command for ping sweep. This command is a ping-like program which uses the Internet Control Message Protocol (ICMP) echo request to determine if a host is up.

fping is different from ping in that you can specify any number of hosts on the command line, or specify a file containing the lists of hosts to ping. If a host does not respond within a certain time limit and/or retry limit, it will be considered unreachable.

Quick Fix

To disable ping sweeps on a network, you can block ICMP ECHO requests from outside sources. This can be done using the following command which will create a firewall rule in iptable.

$iptables -A OUTPUT -p icmp –icmp-type echo-request -j DROP
DNS Enumeration
Domain Name Server (DNS) is like a map or an address book. In fact, it is like a distributed database which is used to translate an IP address 192.111.1.120 to a name www.example.com and vice versa.

DNS enumeration is the process of locating all the DNS servers and their corresponding records for an organization. The idea is to gather as much interesting details as possible about your target before initiating an attack.

You can use nslookup command available on Linux to get DNS and host-related information. In addition, you can use the following DNSenum  script to get detailed information about a domain −

DNSenum.pl

DNSenum script can perform the following important operations −

Get the host’s addresses

Get the nameservers

Get the MX record

Perform axfr queries on nameservers

Get extra names and subdomains via Google scraping

Brute force subdomains from file can also perform recursion on subdomain that has NS records

Calculate C class domain network ranges and perform whois queries on them

Perform reverse lookups on netranges

Quick Fix

DNS Enumeration does not have a quick fix and it is really beyond the scope of this tutorial. Preventing DNS Enumeration is a big challenge.

If your DNS is not configured in a secure way, it is possible that lots of sensitive information about the network and organization can go outside and an untrusted Internet user can perform a DNS zone transfer.