# NMAP

## Introduction to Nmap

Nmap, short for Network Mapper, is a free and open-source tool used for network exploration and security auditing. It allows users to discover hosts and services on a computer network, thus creating a "map" of the network. Nmap is widely used for network inventory, managing service upgrade schedules, and monitoring host or service uptime.

### Installation

Nmap is available for various operating systems, including Windows, Linux, and macOS. To install Nmap:

* **Windows**: Download the installer from the [official Nmap download page](https://nmap.org/download.html) and follow the on-screen instructions.
* **Linux**: Use your distribution's package manager. For example, on Debian-based systems:

  ```bash
  sudo apt-get install nmap
  ```
* **macOS**: Use a package manager like Homebrew:

  ```bash
  brew install nmap
  ```

### Basic Usage

Once installed, Nmap can be used to perform various network scanning tasks. Here are some basic examples:

#### 1. Scanning a Single Host

To scan a single host and list open ports:

```bash
nmap 192.168.1.1
```

This command will display the open ports and the services running on them.

#### 2. Scanning Multiple Hosts

To scan multiple hosts:

```bash
nmap 192.168.1.1 192.168.1.2 192.168.1.3
```

Or, to scan a range of IP addresses:

```bash
nmap 192.168.1.1-10
```

#### 3. Scanning an Entire Subnet

To scan an entire subnet:

```bash
nmap 192.168.1.0/24
```

This will scan all 256 IP addresses in the subnet.

#### 4. Service Version Detection

To detect the version of services running on open ports:

```bash
nmap -sV 192.168.1.1
```

This provides detailed information about the services detected.

#### 5. Operating System Detection

To detect the operating system of a host:

```bash
nmap -O 192.168.1.1
```

This attempts to determine the operating system of the target host.

#### 6. Combining Scans

You can combine different scan options. For example, to perform service version detection and operating system detection together:

```bash
nmap -sV -O 192.168.1.1
```

### Example Output

Here is an example of Nmap output for a scan on a single host:

```kotlin
Starting Nmap 7.80 ( https://nmap.org ) at 2024-11-05 10:23 UTC
Nmap scan report for 192.168.1.1
Host is up (0.00097s latency).
Not shown: 995 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
443/tcp  open  https
```

This output indicates that the host at 192.168.1.1 has ports 22, 80, and 443 open, corresponding to SSH, HTTP, and HTTPS services, respectively.

### Additional Resources

For more detailed information and advanced usage, refer to the [Nmap Reference Guide](https://nmap.org/book/man.html#man-description).