How to make a bootable backup of an entire system HDD that is not coected to internet?

I am using a CentOS environment which is restricted from accessing inteet. I want to create a bootable copy of the entire HDD of the system.

I looked into VMWare Vcenter, but that won't work as I caot coect to network (Network ports are basically disabled).

I also looked into Mondo Rescue, but that has got an avalanche of dependecies that it caot be build on CentOS.

Is there an simple way to get this thing done.