Port Scan Commands

The command "nmap --top-ports 10" is a specific usage of the popular network scanning tool Nmap. Nmap, short for Network Mapper, is a powerful and flexible open-source utility used for network exploration and security auditing. It allows users to discover hosts, services, and vulnerabilities on a network by sending packets and analyzing the responses.

The "--top-ports 10" option in the Nmap command specifies that the scan should focus on the top 10 most common ports used by network services. In networking, ports are virtual endpoints through which network services communicate. Each service generally uses a specific port number for communication, such as port 80 for HTTP or port 443 for HTTPS.

By using the "--top-ports 10" option, Nmap will target the ports most frequently associated with commonly used network services. This selection is based on statistics and research about the prevalence of certain services and their corresponding port numbers.

The top 10 ports typically included in this scan are:

1. Port 21 (FTP): File Transfer Protocol (FTP) is commonly used for transferring files between systems.
2. Port 22 (SSH): Secure Shell (SSH) is a secure protocol used for remote access and secure data transfer.
3. Port 23 (Telnet): Telnet is an insecure protocol used for remote access to network devices.
4. Port 25 (SMTP): Simple Mail Transfer Protocol (SMTP) is used for email transmission between mail servers.
5. Port 80 (HTTP): Hypertext Transfer Protocol (HTTP) is the standard protocol used for web browsing.
6. Port 110 (POP3): Post Office Protocol version 3 (POP3) is an email retrieval protocol.
7. Port 143 (IMAP): Internet Message Access Protocol (IMAP) is an email retrieval and storage protocol.
8. Port 443 (HTTPS): Hypertext Transfer Protocol Secure (HTTPS) is the secure version of HTTP used for encrypted web browsing.
9. Port 3389 (RDP): Remote Desktop Protocol (RDP) allows remote access to Windows systems.
10. Port 5900 (VNC): Virtual Network Computing (VNC) is a graphical desktop sharing system.

When running the "nmap --top-ports 10" command, Nmap will scan the target network and probe these specific ports to determine if they are open, closed, or filtered. Open ports indicate that a service is actively listening and accepting connections on that port, potentially revealing the presence of a specific network service. Closed ports mean that no service is listening on that port, while filtered ports imply that a firewall or network device is blocking the access to that port.

It's important to note that this command only scans a limited number of ports, which are the most commonly used ones. To perform a more comprehensive scan, you can use different options and parameters with Nmap to scan a wider range of ports or even the entire port range.