Could not resolve host: github.com

[numidio]

Hello, I've this problem.. why?

root@red:/home/red# git clone https://github.com/LionSec/katoolin.git && cp katoolin/katoolin.py /usr/bin/katoolin
Cloning into 'katoolin'...
fatal: unable to access 'https://github.com/LionSec/katoolin.git/': Could not resolve host: github.com