Cloning a VirtualBox machine running CentOS

Link: Cloning a VirtualBox machine running CentOS causes network interfaces to fail

VBox Virtual Networks Quick Guide

While I'm writing this post, VirtualBox 4.3.4 "NAT networks" (Network Address Translation Service) don't work properly (still experimental), so to have an internal network where VMs are accessible by Host but NOT from outside, and VMs are able to access networks outside host (as internet), I had to:

1) on Host VirtualBox Manager > file > preferences >  network > host-only networks > add; on the (guest) VM settings > network > attached to > host-only adapter > set proper name

2) on Host, enable routing on the kernel:
$ sudo vi /etc/sysctl.conf
uncomment "net.ipv4.ip_forward=1"

3) on Host, enable NAT outside:
$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$ sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

To make it persistent under a Debian/Linux Mint host, create a new ifup rule:

$ sudo vi /etc/network/if-up.d/iptables_NAT_vboxnet_out

#!/bin/sh
#
# Don't bother to do anything for lo or VBoxNets.
IFTYPE=$(echo "$IFACE" | cut -c1-2)
if [ "$IFTYPE" = lo -o "$IFTYPE" = vb ]; then
    exit 0
fi
# Only run from ifup.
if [ "$MODE" != start ]; then
    exit 0
    else
    iptables -t nat -A POSTROUTING -o "$IFACE" -j MASQUERADE
fi

$ sudo chmod ugo+x /etc/network/if-up.d/iptables_NAT_vboxnet_out

Reestart the Host to test.

Installing VirtualBox (Bin Package)

Go to

https://www.virtualbox.org/wiki/Linux_Downloads

download "All distributions" (runs a bin installer)

$ sudo sh VirtualBox-VERSION-SYSTEM.run

After installing, go to https://www.virtualbox.org/wiki/Downloads

then click on "VirtualBox 4.3.2 Oracle VM VirtualBox Extension Pack"

choose open download directly on VirtualBox


To make VM fit on host screen etc:
running VM > devices > insert guest additions cd image
execute cd installer via SO


To update/upgrade VirtualBox, just make the same process; you'll need to reinstall Extension Pack