Book Image

Network Scanning Cookbook

By : Sairam Jetty
Book Image

Network Scanning Cookbook

By: Sairam Jetty

Overview of this book

Network scanning is a discipline of network security that identifies active hosts on networks and determining whether there are any vulnerabilities that could be exploited. Nessus and Nmap are among the top tools that enable you to scan your network for vulnerabilities and open ports, which can be used as back doors into a network. Network Scanning Cookbook contains recipes for configuring these tools in your infrastructure that get you started with scanning ports, services, and devices in your network. As you progress through the chapters, you will learn how to carry out various key scanning tasks, such as firewall detection, OS detection, and access management, and will look at problems related to vulnerability scanning and exploitation in the network. The book also contains recipes for assessing remote services and the security risks that they bring to a network infrastructure. By the end of the book, you will be familiar with industry-grade tools for network scanning, and techniques for vulnerability scanning and network protection.
Table of Contents (10 chapters)

How to identify open ports

The following are the six port states that are present in Nmap:

  • open: This means that the port is functioning and has a service running or accessing it. The service can thus accept any connections made as per the protocol and service in use on this port.
  • closed: A closed port is not being accessed by any service, there is no service running on it. Thus, no connections made externally will be successful on these ports.
  • filtered: This status is associated with ports from which no response was received due to the packet filtering mechanism present within the network. This might be caused by an intermediate network protection device.
  • unfiltered: This status is associated with the ports that Nmap was not able to determine whether they were open or closed. Mostly ACK scan labels ports to be in unfiltered state; moreover, scans such as SYN and FIN can help...