Port scanning

In this phase, we will perform detection of the ports open for a specific host based on the communication between the host on that port to your machine. This technique helps to determine whether a particular port is open or closed. This technique differs from protocol to protocol. For example, for TCP, the communication and the pattern to conclude a port to be open is different when compared to UDP. Some of the tools that can be used to perform port scanning are Nmap, Nessus, OpenVas, and Wireshark.

The following screenshot shows a sample host scanned using Nmap for port 80. The screenshot shows that the host is up and port 80 with state as open, thus we can determine the host is live. These tools come in handy if the ping is disabled across the network: