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Nmap: Network Exploration and Security Auditing Cookbook

You're reading from   Nmap: Network Exploration and Security Auditing Cookbook Network discovery and security scanning at your fingertips

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Product type Paperback
Published in May 2017
Publisher
ISBN-13 9781786467454
Length 416 pages
Edition 2nd Edition
Languages
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Author (1):
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Paulino Calderon Paulino Calderon
Author Profile Icon Paulino Calderon
Paulino Calderon
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Table of Contents (18) Chapters Close

Preface 1. Nmap Fundamentals 2. Network Exploration FREE CHAPTER 3. Reconnaissance Tasks 4. Scanning Web Servers 5. Scanning Databases 6. Scanning Mail Servers 7. Scanning Windows Systems 8. Scanning ICS SCADA Systems 9. Optimizing Scans 10. Generating Scan Reports 11. Writing Your Own NSE Scripts 12. HTTP, HTTP Pipelining, and Web Crawling Configuration Options 13. Brute Force Password Auditing Options 14. NSE Debugging 15. Additional Output Options 16. Introduction to Lua 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...

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