[CentOS] Cents OS from Bash Shell

From: Adekoya Adekunle <adekunleadekoya at gmail.com>

> I want to know the right command to type from a bash shell so that i can
>    1) Check the version of my cent os
>    2)  Check all the open ports (tcp and udp) on my machine
>    3)  Open a specific port say port 3306 so that a  telnet request from a
> remote machiene can be accepted
>   4)  Disable the effect of 3 above in case I want to

1. cat /etc/centos-release
2. netstat -nltup
3. I let it as a google exercise...

JD