My new website - Hackersfeed.com

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Please visit my new website www.hackersfeed.com

Nmap - The Powerful Network Scanner - Part 3

Today I'm going to explain about about port scanning techniques. There are many port scanning techniques available in nmap. Choose wisely which technique you want to use because there are few port scan techniques which requires special privileges like root or administrator. Those port scan techniques will send RAW packets to target machine during scan.

Before we start you should understand TCP flags and what that means.
SYN- Synchronize - To establish connection with target machine.
ACK- Acknowledge - Target machine sends acknowledge back to sender
RST- Reset - Reset or Try again
FIN- Finish - To stop communication
URG- Urgent - Increase priority
PSH- Push - To make free buffer space


-sS(TCP SYN Scan)
SYN scan is the default and popular scan. It scans thousands of ports quickly .It is also called as stealth scan and half open scan. The reason is it never completes TCP connection to target machine. First it sends SYN packet to establish connection with target machine and wait for response. Target machine will send back SYN/ACK packet if port is open or RST packet if port is closed. If no response received after several re-transmission, nmap mark that port as filtered. The port is also marked if an ICMP unreachable error is received  Here is the sample output

-sT (TCP Connect Scan)
Nmap asks OS to establish connection to target machine port by issuing connect system call.In this scan TCP connection fully established to target machine. Attackers will not use this scan as IDS can easily catch these packets. It is also known as full scan. Here is the sample output

-sU (UDP Scan)
There are few services are using UDP protocol such as DNS,SNMP,DHCP. UDP scaning is slower compares to TCP. Here is the sample output

-sN, -sF, -sX (TCP NULL, FIN, and Xmas Scan)

Null scan (-sN)
Does not set any bits (TCP flag header is 0)

FIN scan (-sF)
Sets just the TCP FIN bit.

Xmas scan (-sX)
Sets the FIN, PSH, and URG flags.
Here is the sample output.

-sO (IP Protocol Scan)
This scan allows you to identify which IP protocols are supported by target machine. This is not technically a port scan. Here is the sample output.

What you can expect in this blog!!!!!!?

Hi Everyone,

In this blog i am gonna explain all topics that covered in CEHv8. I will be explaining you in exam point of view. I will show you few basic and important tools like metasploit,pen tools that used by Ethical Hackers.


Module 01: Introduction to Ethical Hacking

Module 02: Footprinting and Reconnaissance

Module 03: Scanning Networks

Module 04: Enumeration

Module 05: System Hacking

Module 06: Trojans and Backdoors

Module 07: Viruses and Worms

Module 08: Sniffers

Module 09: Social Engineering

Module 10: Denial of Service

Module 11: Session Hijacking

Module 12: Hacking Webservers

Module 13: Hacking Web Applications

Module 14: SQL Injection

Module 15: Hacking Wireless Networks

Module 16: Evading IDS, Firewalls, and Honeypots

Module 17: Buffer Overflow

Module 18: Cryptography

Module 19: Penetration Testing

I will be showing practical sessions in Back track or Kali OS. Do not expect hi fi things.As i said earlier i am at beginner level and am also learning now only.

Don't hesitate to ask you questions and to give feedback.

Welcome Note

 Do the job you love and you'll never work a day in your life -Unknown Person


The term hacker has become a permanent part of our everyday.Every minute of every day there are governments, organized crime, and hacker groups turning the doorknobs on your house looking for an unlocked entry.Are you going to sit idly by and watch as they ransack your belongings,make use of your facilities? The greatest gift you can give yourself is that of education. What you don’t know may not kill you.

The various coverage of security topics in this blog is what helps you more completely understand the minds of hackers and how they work, and it will ultimately be the singular reason you may avoid an attack in the future. Read it carefully. Learn from it. And
practice it.Make no mistake; the digital battlefi eld is very real. It has no beginning, it has no ending, it has no boundaries, and it has no rules. Read this blog, learn from it, and defend yourself, or we may lose this digital war.


I am an amateur in this security field. I know editorial,tutorial is tough one but I will do my best and if my English is bad.

Legal Disclaimer

These resources are for educational and research purposes only. Do not attempt to violate the law with anything enclosed here within. If this is your intention, then leave now.

While using this blog and reading various hacking tutorials, you agree to follow the below mentioned terms and conditions:

• All the information provided in this blog is for educational purposes only. You will be held responsible for any misuse of the information.
•  This blog is totally meant for providing information on " System Security”, "Information Security” and other related topics and is no way related towards the terms "CRACKING” or "HACKING” (Unethical).
• Few articles (tutorials) in this book may contain the information related to "Hacking Passwords” or "Hacking Emails” (Or Similar terms). These are not the GUIDES of Hacking.You shall not misuse the information to gain unauthorized access. However you may try out these hacks on your own computer at your own risk.
• The word "Hack” or "Hacking” that is used in this blog shall be regarded as "Ethical Hacking” respectively.
• Some of the tricks provided here may no longer work due to fixture in the bugs that enabled the exploits. I am not responsible for any direct or indirect damage caused due to the usage of the hacks provided here in this blog.

The Directory Structure

            All the files are grouped together in the directory structure. The file-system is arranged in a hierarchical structure, like an inverted tree. The top of the hierarchy is traditionally called root (written as a slash / )

Here is a generalized overview of common locations of files on a Unix operating system

Directory or file	Description
/	The slash / character alone denotes the root of the filesystem tree.
/bin	Stands for "binaries" and contains certain fundamental utilities, such as ls or cp, which are generally needed by all users.
/boot	Contains all the important files which are required for successful booting process.
/dev	Stands for "devices". Contains file representations of peripheral devices and pseudo-devices.
/etc	Contains system-wide configuration files and system databases.
/home	Contains the home directories for the users.
/lib	Contains system libraries, and some critical files such as kernel modules or device drivers.
/lib64	Contains system libraries, and some critical files such as kernel modules or device drivers, on some 64-bit systems.
/media	Default mount point for removable devices, such as USB sticks, media players, etc.
/mnt	Stands for "mount". Contains filesystem mount points. These are used, for example, if the system uses multiple hard disks or hard disk partitions. It is also often used for remote (network) filesystems, CD-ROM/DVD drives, and so on.
/opt	Contains add-on software. Some large program suites may prefer to be installed here, rather than under /usr.
/proc	procfs virtual filesystem showing information about processes as files.
/root	The home directory for the superuser "root" - that is, the system administrator. This account's home directory is usually on the initial filesystem, and hence not in /home (which may be a mount point for another filesystem) in case specific maintenance needs to be performed, during which other filesystems are not available. Such a case could occur, for example, if a hard disk drive suffers physical failures and cannot be properly mounted.
/sbin	Stands for "system (or superuser) binaries" and contains fundamental utilities, such as init, usually needed to start, maintain and recover the system.
/srv	Server data (data for services provided by system).
/sys	In some Linux distributions, contains a sysfs virtual filesystem, containing information related to hardware and the operating system.
/tmp	A place for temporary files. Many systems clear this directory upon startup; it might have tmpfs mounted atop it, in which case its contents do not survive a reboot, or it might be explicitly cleared by a startup script at boot time.
/usr	Originally the directory holding user home directories,[3] its use has changed. It now holds executables, libraries, and shared resources that are not system critical, like the X Window System, KDE, Perl, etc. (The name "Unix System Resources" is a post hoc backronym[citation needed].) However, on some Unix systems, some user accounts may still have a home directory that is a direct subdirectory of /usr, such as the default as in Minix. (on modern systems, these user accounts are often related to server or system use, and not directly used by a person)
/usr/bin	This directory stores all binary programs distributed with the operating system not residing in /bin, /sbin or (rarely) /etc.
/usr/include	Stores the development headers used throughout the system. Header files are mostly used by the #include directive in C programming language, which historically is how the name of this directory was chosen.
/usr/lib	Stores the required libraries and data files for programs stored within /usr or elsewhere.
/usr/local	Resembles /usr in structure, but its subdirectories are used for additions not part of the operating system distribution, such as custom programs or files from a BSD Ports collection. Usually has subdirectories such as /usr/local/lib or /usr/local/bin.
/var	A short for "variable." A place for files that may change often - especially in size, for example e-mail sent to users on the system, or process-ID lock files.
/var/log	Contains system log files.
/var/mail	The place where all the incoming mails are stored. Users (other than root) can access their own mail only. Often, this directory is a symbolic link to /var/spool/mail.
/var/spool	Spool directory. Contains print jobs, mail spools and other queued tasks.
/var/tmp	A place for temporary files which should be preserved between system reboots.

Types of UNIX & The UNIX operating system

Types of UNIX

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X

The UNIX operating system

The UNIX operating system is made up of three parts; the kernel, the shell and the programs.

The kernel

The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls.

As an illustration of the way that the shell and the kernel work together, suppose a user types rm myfile (which has the effect of removing the file myfile). The shell searches the filestore for the file containing the program rm, and then requests the kernel, through system calls, to execute the program rm on myfile. When the process rm myfile has finished running, the shell then returns the UNIX prompt % to the user, indicating that it is waiting for further commands.

The shell

The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems).

The adept user can customise his/her own shell, and users can use different shells on the same machine.

The tcsh shell has certain features to help the user inputting commands.

Filename Completion – By typing part of the name of a command, filename or directory and pressing the [Tab] key, the tcsh shell will complete the rest of the name automatically. If the shell finds more than one name beginning with those letters you have typed, it will beep, prompting you to type a few more letters before pressing the tab key again.

History – The shell keeps a list of the commands you have typed in. If you need to repeat a command, use the cursor keys to scroll up and down the list or type history for a list of previous commands.

Files and processes

Everything in UNIX is either a file or a process. A process is an executing program identified by a unique PID (process identifier).

A file is a collection of data. They are created by users using text editors, running compilers etc.