nmap scripting enginne [nse] 3 
                                   -- basic notions of LUA/nseAPI scripting language --



                                 [[ The NSE scripts are (pack) in different categories ]]
        "auth, broadcast, brute, default, discovery, exploit, external, fuzzer, intrusive, malware, safe, vuln"
        Configuring our NSE script in one of these categories allows us to call it, and all other scripts within
        that same category using the 'switch' --script <category> <target>



                                    [[ The NSE scripts are divided into 4 sections ]]
        The 'HEAD' contains meta-data that describes the functionality of the module
        "author, impact, category and other descriptive data".

        The 'DEPENDENCIES' (lua libraries needed) to use nmap API syntax

        The 'RULE SECTION' defines the conditions necessary for the script to run.
        This section must contain at least one function from this list: "portrule, hostrule, prerule, postrule".
        For purposes of this tutorial (and most scripts), will focus on "portrule" that can perform checks on
        both the host and port properties before running the script.

        The 'ACTION SECTION' defines the script logic, In the tradition of K&R (Kernighan & Ritchie)
        I will just give out "Hello, world!" for any open port HTTP using the API 'return' to display output.



                                              [[ hello.nse script ]]
----------------------------------------------------------------------------------------------------------------------------
 
--  THE HEAD SECTION --
description = [[
 
Author: r00t-3xp10it
NSE LESSON 3 - my first nse scrip
 
Some Syntax examples:
nmap --script-help hello.nse
nmap -sS -Pn -p 80 --script hello.nse <target>
nmap -sS -Pn -p 80 --script discovery <target>
 
]]
 
author = "r00t-3xp10it"
-- Configuring our NSE script in one of these categories allows us to call it
-- and all other scripts within that same category using --script <category> <target>
categories = {"discovery", "safe"}
 
 
  -- THE DEPENDENCIES SECTION --
  -- lua libs needed by nmap API programing syntax
  -- In the follow line 'local' defines a local variable named 'http' that requires 'http.lua' library
  local http = require "http"             --> https://nmap.org/nsedoc/lib/http.html
  local shortport = require "shortport"   --> https://nmap.org/nsedoc/lib/shortport.html
 
 
    -- THE RULE SECTION --
    -- A portrule that matches likely HTTP services.
    -- Return value: true if the port is likely to be HTTP, false otherwise.
    portrule = shortport.http         --> https://nmap.org/nsedoc/lib/shortport.html#http
 
 
-- THE ACTION SECTION --
action = function(host, port)          --> host its the target host-ip inputed | port its the port selected by nmap -p 80 switch
    return "Hello world!"              --> print "hello world" if found any http port open using 'return' API call
end
 
----------------------------------------------------------------------------------------------------------------------------

COPY SCRIPT TO NMAP DATABASE => sudo cp hello.nse /usr/share/nmap/scripts/hello.nse
UPDATE NMAP DATABASE => sudo nmap --script-updatedb
RUN NSE SCRIPT => sudo nmap -sS -Pn -p 80 --script hello.nse <target>



_EOF