Book Image

Nmap: Network Exploration and Security Auditing Cookbook - Second Edition

By : Paulino Calderon
Book Image

Nmap: Network Exploration and Security Auditing Cookbook - Second Edition

By: Paulino Calderon

Overview of this book

This is the second edition of ‘Nmap 6: Network Exploration and Security Auditing Cookbook’. A book aimed for anyone who wants to master Nmap and its scripting engine through practical tasks for system administrators and penetration testers. Besides introducing the most powerful features of Nmap and related tools, common security auditing tasks for local and remote networks, web applications, databases, mail servers, Microsoft Windows machines and even ICS SCADA systems are explained step by step with exact commands and argument explanations. The book starts with the basic usage of Nmap and related tools like Ncat, Ncrack, Ndiff and Zenmap. The Nmap Scripting Engine is thoroughly covered through security checks used commonly in real-life scenarios applied for different types of systems. New chapters for Microsoft Windows and ICS SCADA systems were added and every recipe was revised. This edition reflects the latest updates and hottest additions to the Nmap project to date. The book will also introduce you to Lua programming and NSE script development allowing you to extend further the power of Nmap.
Table of Contents (18 chapters)
13
Brute Force Password Auditing Options
17
References and Additional Reading

Detecting suspicious SMTP servers


Compromised servers might have rogue SMTP servers installed and abused by spammers. System administrators can use Nmap to help them monitor mail servers in their network.

This recipe shows how to detect rogue SMTP servers with Nmap.

How to do it...

Open your terminal and enter the following Nmap command:

$ nmap -sV --script smtp-strangeport <target>

If a mail server is found on a nonstandard port, it will be reported in the script output section:

   PORT    STATE SERVICE  VERSION 
   9999/tcp open  ssl/smtp Postfix smtpd 
   |_smtp-strangeport: Mail server on unusual port: possible malware 

How it works...

The smtp-strangeport script was submitted by Diman Todorov. It detects SMTP servers running on nonstandard ports, which is an indicator of rogue mail servers. If an SMTP server is found running on a port other than 25, 465, and 587, this script will notify you.

The arguments -sV --script smtp-strangeport make nmap start service detection and launch the NSE...