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Definition of Nmap

What is Nmap?

Nmap, or "Network Mapper," is a free, open-source tool primarily used for network discovery and security, as well as auditing network inventory, managing service upgrade schedules, and monitoring host or service uptime. It's an essential instrument for conducting penetration tests because its extensive resources can scan single-host networks or those with a hundred or more. It can identify the hosts available on a network, the services they are offering, what operating systems and versions they are running, what type of packet filters/firewalls are in use, and dozens of other factors.

This information helps companies identify vulnerabilities in their security infrastructure that could be exploited by malicious hackers and develop more robust defense measures.

What is Nmap used for?

Nmap is widely used by security professionals and ethical hackers for vulnerability assessments and penetration testing. However, as an open-source tool, malicious hackers also use it to assess the security of their targets and find weaknesses they can exploit. This illustrates the necessity of regular security audits.

Specifically, Nmap searches a network for hosts and services to which it then sends information. The hosts and services respond, and Nmap uses their responses to create a map of the network, similar to how radar works. The map contains detailed information on the function of each port and how or what is using it. It also displays how hosts connect to the ports, what makes it through the firewall and doesn't, and any security issues it discovers.

What are the types of Nmap scans?

Nmap scans are able to conduct vulnerability detection, backdoor detection, vulnerability exploitation, and network discovery. There are a variety of scans it uses to perform these tasks. There are basic scans to determine the devices running on a network and that check a single host. More complex scans suitable for large networks include:

  • stealth scanning for making a TCP connection
  • version scanning to determine application versions
  • OS scanning to identify the underlying operating system and its uptime
  • aggressive scanning that combines these tests
  • script scanning and traceroute
  • port scanning
  • multiple host scanning.

Choosing the best scan for your system depends on your specific needs, the size of your network, and how much time you have to conduct the test.

Key Takeaways

  • Nmap is an open-source tool used to scan networks to identify vulnerabilities.
  • It’s an essential tool in penetration testing.
  • Nmap can also be used by malicious hackers to map weaknesses in a network.
  • Nmap offers many types of thorough scans for different network types and sizes.
  • Fun fact: Nmap has been featured in many film scenes involving hacking.

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