Book Image

Nmap 6: Network Exploration and Security Auditing Cookbook

Book Image

Nmap 6: Network Exploration and Security Auditing Cookbook

Overview of this book

Nmap is a well known security tool used by penetration testers and system administrators. The Nmap Scripting Engine (NSE) has added the possibility to perform additional tasks using the collected host information. Tasks like advanced fingerprinting and service discovery, information gathering, and detection of security vulnerabilities."Nmap 6: Network exploration and security auditing cookbook" will help you master Nmap and its scripting engine. You will learn how to use this tool to do a wide variety of practical tasks for pentesting and network monitoring. Finally, after harvesting the power of NSE, you will also learn how to write your own NSE scripts."Nmap 6: Network exploration and security auditing cookbook" is a book full of practical knowledge for every security consultant, administrator or enthusiast looking to master Nmap. The book overviews the most important port scanning and host discovery techniques supported by Nmap. You will learn how to detect mis-configurations in web, mail and database servers and also how to implement your own monitoring system. The book also covers tasks for reporting, scanning numerous hosts, vulnerability detection and exploitation, and its strongest aspect; information gathering.
Table of Contents (18 chapters)
Nmap 6: Network Exploration and Security Auditing Cookbook
Credits
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
References
Index

Discovering hosts with TCP ACK ping scans


Similar to the TCP SYN ping scan, the TCP ACK ping scan is used to determine if a host is responding. It can be used to detect hosts that block SYN packets or ICMP echo requests, but it will most likely be blocked by modern firewalls that track connection states.

The following recipe shows how to perform a TCP ACK ping scan and its related options.

How to do it...

Open a terminal and enter the following command:

# nmap -sP -PA <target>

How it works...

A TCP ACK ping scan works in the following way:

  • Nmap sends an empty TCP packet with the ACK flag set to port 80

  • If the host is offline, it should not respond to this request

  • If the host is online, it returns an RST packet, since the connection does not exist

There's more...

It is important to understand that there will be cases when this technique will not work. Let's launch a TCP ACK ping scan against one of these hosts.

# nmap -sP -PA 0xdeadbeefcafe.com 


Note: Host seems down. If it is really up,...