Nmap is an open-source network exploration and security auditing tool, initially released in 1997. The Nmap Scripting Engine (NSE) allows users to automate networking tasks through scripts written in Lua, enhancing Nmap's capabilities and facilitating complex network reconnaissance. Scripts are categorized based on their functions, and community contributions maintain the relevance of NSE in addressing emerging security threats.

1. Introduction to Nmap
• • Network Mapper (Nmap) is an open-source
tool for network exploration and security
auditing.
• • Developed by Gordon Lyon (Fyodor) and first
released in 1997.
• • Widely used for network inventory,
managing service upgrade schedules, and
monitoring host or service uptime.

2. What is the Nmap Scripting Engine
(NSE)?
• • NSE is a powerful feature of Nmap that
allows users to write and share simple scripts
to automate a wide variety of networking
tasks.
• • Introduced in Nmap version 4.50.
• • Scripts are written in Lua, a lightweight
programming language.

3. Benefits of Using NSE
• • Enhances Nmap's capabilities beyond simple
port scanning.
• • Automates complex network reconnaissance
and exploitation tasks.
• • Extensible: Users can write custom scripts
for specific needs.
• • Community-driven: Many scripts are shared
and improved by the security community.

4. How NSE Works
• • NSE scripts are stored in the 'scripts'
directory of Nmap.
• • Scripts are executed in parallel with Nmap's
core scanning functions.
• • Each script can specify its own arguments
and categories.

5. Script Categories
• • Auth: Authentication bypass and brute force
attacks.
• • Broadcast: Network discovery using
broadcast and multicast.
• • Default: Basic scripts that run with the '-sC'
option.
• • Discovery: Network discovery tasks.
• • Dos: Denial of Service attacks.
• • Exploit: Exploit vulnerabilities.

6. Example Scripts
• • http-enum: Enumerates directories used by
web servers.
• • smb-os-discovery: Attempts to determine
the OS of a remote SMB server.
• • ftp-anon: Checks for anonymous FTP logins.
• • ssl-heartbleed: Checks for the Heartbleed
vulnerability in SSL/TLS.

7. Running NSE Scripts
• • Use the '--script' option followed by the
script name(s):
• ```
• nmap --script <script-name> <target>
• ```
• • Run multiple scripts by specifying a comma-
separated list or using wildcards:
• ```
• nmap --script script1,script2 <target>

8. Writing Your Own NSE Scripts
• • Scripts are written in Lua and typically have
four main sections:
• - Head: Metadata about the script.
• - Rule: When the script should run.
• - Action: Main logic of the script.
• - Post: (Optional) Clean up actions.
• • Example skeleton:
• ```lua
• description = [[

9. Use Cases
• • Network inventory and monitoring.
• • Vulnerability assessment and penetration
testing.
• • Compliance auditing.
• • Security research and incident response.
• • Custom automation for specific network
tasks.

10. Conclusion
• • The Nmap Scripting Engine extends Nmap's
capabilities far beyond basic scanning.
• • NSE scripts are versatile, allowing for
complex network tasks to be automated.
• • Community contributions keep NSE relevant
and up-to-date with emerging security
threats.