Skip to main content

Virtualbox networking workarounds

By
Virtualbox networking setup is a tedious task to understand and implement the very first time. This is mainly because of the multiple network options that it provides and the different locations used to setup those networks. Please follow this virtualbox networking manual to learn about virtualbox networking options. This post builds on the above manual to demonstrate a custom case for setting up a local network of 4 virtual machines (VMs) with internet access and also give the host access to these machines.

The specific networking requirement was not addressed by any of the network options provided by virtualbox. Let's understand it through the table provided in the above manual:

ModeVM→Host VM←Host VM1↔VM2 VM→Net/LAN VM←Net/LAN
Host-only + + + – –
Internal – – + – –
Bridged + + + + +
NAT + Port forward – + Port forward
NATservice + Port forward + + Port forward
Requirement + + + + Port forward

As can be seen, the requirement is to have host access the VMs seamlessly but do not allow the outside network to access the VMs without port forwarding. A workaround to fulfill this requirement is to set up two networks that together satisfy the requirements. From the above table, two networks can be:
  1. A host-only network and a NAT
    OR 
  2. A host-only network and a NAT service.
It was decided to setup a host-only network and a NAT service network. The setup is simple,

Host-only network

  1. Navigate to File -> Host Network Manager (This path may change based on virtualbox version.)
  2. Create a new network
  3. Go to "properties" tab and edit the properties of the network adapter. Apply the properties.

    NOTE: Make sure the IPv4 address doesn't include network address
    For example, in the settings shown in the image, the IPv4 address should not be 10.0.1.0/24 but 10.0.1.1/24 otherwise it causes issues.
  4. If you want DHCP managed IPs, tick the DHCP checkbox.
  5. Edit the DHCP server properties in the "DHCP server" tab. Apply the settings

Now edit the network settings for all the VMs and add a new adapter with host-only network as below.


 

NAT service network / NAT network

  1. To setup this network, navigate to Virtualbox -> preferences -> Network (This path may change based on virtualbox version.)
  2. Create a new network
  3. Navigate to preferences tab and configure necessary settings.

    In the image, the "Supports DHCP" checkbox is disabled. This is because the intention is to setup static IPs on all the VMs on the NAT network interface.

Again edit the network settings for all the VMs and add a new adapter with NAT network.


Test

(Re)start the VMs and check their network interfaces.


Apart from the loopback address, there are two other interfaces, enp0s3 on 10.0.1.1/24 host-only network and enp0s8 on 10.0.2.0/24 NAT network.


Conclusion

Even though virtualbox network modes may not cover all the networking requirements, a combination of multiple networking modes can be used to set up-to 4 network interfaces on the VMs to achieve the desired configuration.
Labels:

Comments

Post a Comment

Popular posts from this blog

Using static IPs in Linux

By
It is often a requirement to assign static IP addresses to some important and permanent network interfaces. This is to avoid setting up a local DHCP server or relying on IP given by your network provider which may not be stable. This post shows steps to configure static IPs in Linux using Ubuntu 16.04 and Ubuntu 18.04 distros. We are considering two distros as network configuration has changed significantly in Ubuntu 18.04. There are two general steps to be followed: 1. Configure the network interface and assign a static IP. 2. Restart interface for the changes to take effect. Ubuntu 16.04  The current interfaces on the system are as follows: As can be seen, enp0s8 interface does not have any IP. Let's assign a static IP to it. In case you already have an interface with a DHCP assigned IP, you just need to change that IP and make it static. Edit the /etc/network/interfaces file and add the following code block. Prefer using the IP address range available for pri...
Post a Comment
Read more

Local domain name resolution using /etc/hosts

By
The /etc/hosts file is a powerful mechanism for managing the information about hosts in the local network in the absence of a local DNS server. Setup We have 4 VMs in the local /24 network. The following are the details: vm-1-ubuntu-16-04 - 10.0.1.11 vm-2-ubuntu-16-04 - 10.0.1.12 vm-1-ubuntu-18-04 - 10.0.1.21 vm-2-ubuntu-18-04 - 10.0.1.22 The VMs are reachable via their IP address but not by their hostnames. This is problematic because we have to remember their IP addresses everytime we want to access these hosts. It is would be much simpler to remember and access the servers by their hostnames. For that we need some sort of mapping between the IP addresses and their corresponding host names. There are 3 common ways of achieving this mapping. Setup a DNS server which handles resolution for your local network. Use an existing DNS server of the local Internet Service Provider (ISP) or any other higher level ISP. Note that a public static IP address is required for this s...
Post a Comment
Read more

Simple HTTP Server in Python

By
Have you ever come across a need to share a file over a local network to a number of machines? Have you ever felt the need to share output of a task in text files available at a web-endpoint? Often, there is a requirement to quickly setup a light-weight web-server for such requirements. Python provides the easiest way to setup a simple HTTP server for such use cases with a single command. Python comes pre-installed with Linux as many of the linux libraries use python in background. Therefore there is no extra overhead of installing python. With support for python2 getting stopped in April 2020, many of the newer versions of linux distros come with default python3. Therefore this post will focus on setting up an HTTP server using both python2 and python3. We will be using Ubuntu 16.04, however it will work for majority of the linux systems where python comes pre-installed. Preparation Steps to follow before starting the server: Make sure you are in the directory which you want ...
Post a Comment
Read more