Simple Scripts for Auditing

If you’re used to using nmap, you already know how awesome it is. You can use it for many types of auditing and network security chores, such as scanning ports or identifying operating systems on remote machines. But, if you ever find yourself in a situation where nmap isn’t available to you, know that you can do some of your nmap chores with some simple shell scripts. Let’s begin with something simple.

Identifying an Operating System

You can get a rough idea of what operating system is running on another machine by pinging it, and looking at the Time-to-Live (TTL) figure in the response. Here’s how it works:

• 64: If the TTL of a ping response is 64, then the operating system of the target machine is Linux, some sort of BSD, or macOS.
• 128: A 128 TTL indicates that the target machine is running Windows.
• 255: This indicates that the target machine is running either Solaris or a Solaris clone, such...