Question

Which netcat command is an example of port scanning?

Option 1: nc -l -p port_number > /test/
Option 2: nc 80
Option 3: nc -v -z target port-range
Option 4: nc -l

Answer 1

The netcat command that is an example of port scanning is `nc -v -z target port-range`

Option 3: `nc -v -z target port-range`.

Step-by-step explanation:

Netcat (nc) is a versatile networking utility that can be used for various purposes, including port scanning. In Option 3, the command `nc -v -z target port-range` signifies a verbose (`-v`) and zero-I/O mode (`-z`) scan on a specified target within a specified port range. The `-z` flag is specifically designed for scanning, as it does not initiate actual data transfer but checks for the open or closed status of the specified ports.

The `target` represents the destination host or IP address, and `port-range` denotes the range of ports to be scanned. For example, `nc -v -z 192.168.1.1 20-100` would scan ports 20 to 100 on the host with the IP address 192.168.1.1. If a port is open, it will be marked as such in the output.

This form of port scanning is essential for security professionals and network administrators to identify open ports on a system. It helps in assessing potential vulnerabilities and securing systems against unauthorized access. The combination of the `-v` (verbose) and `-z` (zero-I/O) flags makes this netcat command an effective and informative tool for port scanning without establishing a full connection or transferring data.