Ubuntu – How to install deb packages offline to install software and keep it updated in Ubuntu 16.04

debpackage-managementserver

I am in a company with local network configured to forbid any network connection from my floor, but I have an online springboard host which can connect with my three virtual machines. In other words I have an online machine and three offline machines to build a cluster. They are both Ubuntu server 16.04 with exactly the same version.

Ubuntu Server doesn't come with some software I need, such as ssh and vim. I was able to bundle all dependencies online, and use nc -l to push them to three offline machines.

But what can I do next to install those .deb files on my offline machines?

I can't use apt-offline, snaptic… Because I am offline and these systems are bare without any tools, no GUI tools. My USB port is also not available, and no CD/DVD drive is available.

So the only thing I can do is copy all the .deb files under /var/cache/apt/archives on my online machine to the offline virtual machines. Having done so, how can I install all the software so that I can maintain the always offline VMs up to date with online one? It makes sense to be sustainable…