Nmap
Overview
used to discover hosts
Host (network)
A network host is a computer connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network. A network host is a network node that is assigned a network layer host address....
and services
Web service
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
on a computer network
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
, thus creating a "map" of
the network. To accomplish its goal, Nmap sends specially crafted packets to the target host and then analyzes the responses.
Unlike many simple port scanners that just send packets at some predefined constant rate, Nmap accounts for the
network conditions (latency fluctuations, network congestion
Network congestion
In data networking and queueing theory, network congestion occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queueing delay, packet loss or the blocking of new connections...
, the target interference with the scan) during the run.
Also, owing to the large and active user community
Community
The term community has two distinct meanings:*a group of interacting people, possibly living in close proximity, and often refers to a group that shares some common values, and is attributed with social cohesion within a shared geographical location, generally in social units larger than a household...
providing feedback and contributing to its features, Nmap has been able to extend its discovery capabilities beyond simply figuring out whether a host is up or down and which ports are open and closed; it can determine the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
of the target, names and versions of the listening services, estimated uptime, type of device, and presence of a firewall
Firewall (computing)
A firewall is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass....
.
Nmap runs on Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
, Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
, Solaris
Solaris Operating System
Solaris is a Unix operating system originally developed by Sun Microsystems. It superseded their earlier SunOS in 1993. Oracle Solaris, as it is now known, has been owned by Oracle Corporation since Oracle's acquisition of Sun in January 2010....
, HP-UX
HP-UX
HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...
and BSD variants (including Mac OS X), and also on AmigaOS
AmigaOS
AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...
and SGI IRIX.
