May 6, 2021

Nmap Howto

Nmap is a network computer scanner that can look for various things on a computer it finds on the network, like OS type, ports open and programs/services/servers that use those ports, this is commonly used to find holes in your own network so you can do something about them, also people with nasty intent use it to find ways to do bad things, so it’s a double edged sword. Whatever you do, get permission from some appropriate organization/sysadmin in charge of something, they get feisty when nmap runs amok on the network, possibly for good reason.

command what it does
nmap -F -T5 -sS 1.2.3.4 scans for open ports on IP 1.2.3.4 (you could also do 1.2.3.0/24 to scan a whole 255.255.255.0 subnet for the same thing)
nmap -sS -sU -sR -P0 -A -v 1.2.3.4 scans for TCP (sS) UDP (sU) portmap (sR) with OS/version detection (A) info and prints our Verbose (v) output on the machine at 1.2.3.4. Make sure you have permission to run this on their machine, otherwise you won’t make any friends doing it 🙂