The Internet Control Message Protocol (ICMP) is like the TCP protocol; both support protocols in the internet protocol suite. ICMP is used for checking live systems; ping is the most well-known utility that uses ICMP requests. Its principle is very simple—ICMP scanning sends requests to hosts and waits for an echo request to check whether the system is alive. An example of a ping sweep is shown here: ping <target>:
The ping sweep is a technique of ICMP scanning, but it scans a range of IP addresses.
There are many TCP services scanning techniques, such as:
- Full open scan: This is done when the three-way handshake is completed ...
