How to use Nmap for port scanning and service identification?

Today I will focus on how to use Nmap for port scanning and service identification. Nmap is a powerful network scanning tool, which can help us quickly understand the open ports and running services of the target host.

1. What is Nmap?

Nmap (Network Mapper) is an open source network scanning tool for discovering information such as open ports, network services, and operating system types on hosts. It is one of the indispensable tools in penetration testing and network management.

2. Steps for port scanning and service identification using Nmap

Below we will use a simple case to introduce how to use Nmap for port scanning and service identification:

Case: Scan the open ports and running services of the target host

Step 1: Open a terminal and start Nmap

In the Kali Linux terminal, enter the following command to start Nmap:

nmap

Step 2: Do a basic port scan

Enter the IP address of the target host and perform a basic port scan. For example:

nmap <目标IP地址>

Step 3: Perform service and version identification

Use -sVparameters for service and version identification. This will attempt to identify the services running on each open port along with their version information.

nmap -sV <目标IP地址>

Step 4: Do a more detailed scan

If you need more detailed scan results, you can use -Aparameters to perform a comprehensive scan, including OS version identification, script scan, etc.

nmap -A <目标IP地址>

3. Case presentation

Operating procedures:

1. Target selection: Select a target system to be scanned. We assume that the target system is a virtual web server.

2. Nmap Scan: Use the Nmap tool to perform port scanning and service identification.

3. Analyze Results: Analyze Nmap scan results to view open ports and identified services.

How to use the tool and demo:

1. Nmap：

   Perform basic port scanning and service identification commands. Suppose the target IP address is 192.168.1.100:

   nmap -p- -sV 192.168.1.100
   

   In the above command:

   • -p-: Scan all ports.
   • -sV: Perform service identification.

Summarize:

Nmap is a powerful network scanning tool that can help you assess the security of your system and find potential vulnerabilities and services. The above is the process of using the Nmap tool for port scanning and service identification. Note that the targets and commands in the examples are fictitious and are used only to illustrate how to use Nmap. In practice, you need to be fully aware of laws, regulations and ethics, and only test when legally authorized.

4. Precautions and Code of Ethics

When using Nmap for port scanning and service identification, it is important to follow ethical guidelines and legal regulations. Unauthorized scans may interfere with the target system, resulting in unwanted consequences.