Before diving deeper into Nmap scripting, it’s important to have a basic understanding of Lua, the programming language used to write Nmap scripts.
Lua is a powerful, efficient, lightweight, embeddable scripting language. It’s designed to be simple, small, portable, and fast. Lua supports procedural programming, object-oriented programming, functional programming, and data-driven programming.
Here’s a very brief overview of Lua:
1. Variables and Types
In Lua, you have numbers, strings, booleans, tables, functions, nil, user data, and threads. Here’s how to declare them:
You can declare a function using the function keyword:
3. Control Structures
Lua supports the usual control structures: if, while, for, and repeat:
Tables in Lua are associative arrays, which means they can be indexed not only with numbers but with any value (except nil). They can be used as arrays, lists, dictionaries, sets, etc.:
Lua modules are similar to a library in C or a package in Java. You can create a Lua module by creating a file, writing Lua code in it, and then using the require function to import it into other scripts.
- This is just a crash course on Lua. For a more comprehensive understanding, consider reading the Programming in Lua book by Roberto Ierusalimschy, the chief architect of Lua.
Once you’re familiar with Lua, you can start writing powerful scripts for the Nmap Scripting Engine. Remember to always use such scripts responsibly and within legal and ethical boundaries.