TCP scanning using NMAP

What is Nmap

• Nmap (Network Mapper) is a free and open source (license) utility.
• Nmap can network discovery and security auditing.
• Many systems and network administrators also find it useful for tasks such as
• network inventory
• managing service upgrade schedules
• monitoring host
• service uptime
• Nmap uses raw IP packets in novel ways to determine
• what hosts are available on the network
• what services (application name and version) those hosts are offering
• what operating systems (and OS versions) they are running
• what type of packet firewall are in use
• and dozens of other characteristics

What is TCP Scanning

• The two basic scan types used most in Nmap are
• TCP connect scanning
sockets programming uses a system call named connect to begin a TCP connection to a remote site. If connect succeeds, a connection was made.This allows a basic type of port scan, which attempts to connect to every port in turn, and notes whether or not the connection succeeded. Once the scan is completed, ports to which a connection could be established are listed as open, the rest are said to be closed. 
• TCP SYN scanning
When a TCP connection is made between two systems, a process known as a "three way handshake" occurs. This involves the exchange of three packets, and synchronises the systems with each other. 

Nmap Practical using Nmap tools

Step 1 : Open Zenmap in your computer

Step 2 : In Target Filed Write IP Address or Website (Target System) and click on scan button

Step 3 : You can find open port list if they are otherwise u can't get any open port

Step 4 : You can find Traceroute path on Topology tab

Step 5 : You can find all the host details in Host Details tab

How to Install Nmap(zenmap) in Windows and Linux

Download the Software Form this source:Nmap

How to Install Nmap(zenmap) in Linux RPM