switchport port security?

Can someone explain to me in a noob friendly way what exactly this command does?

 

Example:

Lets say you want to run a ftp server. Def port is 21 . As soon as set your router up to direct all port 21 traffic to your server, the snoopers have it located in <2min. Then the hacker will try to break in to it, they are relentless 24/7. But if you do redirect to a port >1024 will get you away from the std snoopers/hackers. So if you pick port 15021, you will have your router redirect port 15021 to your server. (ftp.myserver.xyz:15021) You are now away from the hackers snoopers and should be clear. You should make sure you pick a port that gamers do not use, to remain hidden. You can also set your router up NOT to respond to ping on the WAN side to make it more secure. If you ftp server is capable of running a log, set it to log on failed password attempts or all logins/errors. This will let you know if someone is attempting to connect to your server.

Make sure you use a strong passwords anytime you setup any hardware (including router) that will be exposed to the www.

 

switchport port-security on Cisco IOS?
It basically lets you set what and how many mac addresses are allowed to talk on that switch port and what to do if an unauthorized mac address is detected or if the max number of allowed hosts is exceeded.

For example:
interface GigabitEthernet0/2
switchport port-security maximum 6
switchport port-security
switchport port-security violation restrict
!
Allows a maximum of 6 unique mac-addresses. Restrict sends a syslog alert and prevents additional devices from passing traffic through this switch port.