"...For a system administrator who is aware of system
security, it is important to carry out a scanning of their own
network, and look for vulnerabilities before others do it with not
so good intentions.
There are several scanning tools for this purpose, but the
article will only look at nmap. Nmap is among the most complete
scanners and security tools.
Nmap allows the system administrator to scan the networks in
order to know which servers are active and which services they
offer. For this purpose, nmap offers several scanning techniques.
This article will work on a limited number of them, reviewing
(maybe teaching?) some aspects of TCP protocol."
