Manage Debian or Ubuntu based systems offline using Keryx

I still remember how much labor I did in order to get Ubuntu running on my home desktop which was supposed to stay offline. As you might have guessed, the whole trouble was with the post-installation part - the updates, installation of other useful packages etc. Because of no Internet connectivity I had to carry the CPU to my friend's house and get everything done. Keryx is something I could have really used then. Its usefulness could be easily understood from the fact that I would have only carried a USB then, rather than a whole CPU .