NSE:banner

A useful technique in reconnaissance is grabbing banners.  There are a few ways to achieve this goal.  Most often you will gain all the information you will need from a simple nmap or even a quick netcat or even hping3.

Banners provide us with information about the port we are investigating.  Here are some additional ways to retrieve information about specific ports that are similar to banner grabbing.

(nmap -sS -sV -p# [ip])

(nc -vn [ip][port])

(hping3 -S -p# [ip] -I [interface name])

Above you can see that I am choosing port 22.  I have turned off the ping probe part of the nmap process and select the banner NSE script with (-sV --script=banner) 

Below you will see the command I used. 

 #nmap -Pn -p22 -sV --script=banner [IP]

 Next steps: investigate to see how old dropbear_2016.74 is

Reference:

[1] https://nmap.org/nsedoc/scripts/banner.html

[2] https://www.studytonight.com/network-programming-in-python/banner-grabbing