Vagrant is a handy and easy-to-use Virtual Machine tool that can be used within your command-line interface. In a nutshell, it makes it easy to create and configure lightweight, reproducible developer environments.

In this mini course, you will learn all about virtualization. You will learn how to set up a Vagrant environment, build your own VM, as well as Vagrant commands which you can use from the command line.

In the latter half of the course, you will learn how to work with vagrantfile, networking, and data sharing. In all, this is your crash course for understanding the fundamentals of Vagrant.

A Guide to Vagrant and Virtual Machines

# Networking

## Private IP addresses

Some IP addresses are set aside so that they can’t be used in the public space/Internet.

These IP addresses are for internal private use only and are not routable on the public internet.

The public and private IP addresses lie in specific ranges, and we can use these ranges to identify whether a given IP is private or public.
| From    |  To  |
| --- | --- |
|10.0.0.0 | 10.255.255.255 |
|    172.16.0.0 |  172.31.255.255   |
|  192.168.0.0   |   192.168.255.255  |

Any IP address residing between these ranges are private addresses.

## Public IP addresses

This course does not require a deep understanding of public IP addresses. We will only look into classful addressing of public IPs to better understand them.

In classful addressing, different ranges of IP addresses are assigned specific classes, as shown in the table below. Each class of IP addresses serves a specific function.

| Class | From | To |
| --- | --- | --- |
| A | 0.0.0.0 | 127.255.255.255 |
| B | 128.0.0.0 | 191.255.255.255 |
| C | 192.0.0.0 | 223.255.255.255 |
| D | 224.0.0.0 | 239.255.255.255 |
| E | 240.0.0.0 | 255.255.255.255 |

Classes **A, B, and C** are publicly available IP addresses on the internet. These classes contain **unicast addresses**. In the case of unicast addresses, only one single device on the internet is trying to connect to another single device.
Whereas, Class **D** consists of **multicast** addresses, which means one device can connect to multiple devices. These are used in enterprises for meetings, etc. These addresses are not available on the public internet.

Lastly, **Class E** IP addresses are reserved for future or experimental purposes only.


Now, let’s get back to our `Vagrantfile` and implement some network-based settings.

# Configure network settings

The `Vagrantfile` generated in the last lesson is shown below.

Open up your `Vagrantfile`.
```
Vagrant.configure("2") do |config|
  config.vm.box = "centos/7"
  config.vm.hostname = "server.example.com"
  config.vm.provider "virtualbox" do |vb|
    vb.memory = "1024"
    vb.cpus = "2"
  end
end
```
## Assign a private IP
Let's try to assign a private IP address to our Virtual Machine.
```
Vagrant.configure("2") do |config|
  config.vm.box = "centos/7"
  config.vm.hostname = "server.example.com"
  config.vm.network "private_network", ip: "192.168.10.1"
  config.vm.provider "virtualbox" do |vb|
    vb.memory = "1024"
    vb.cpus = "2"
  end
end
```
Remember the private IP ranges discussed above. The IP address assigned in the `Vagrantfile` above lies in one of those ranges.


## Assign a public IP
Now, let’s try to assign a public IP address to our Virtual Machine using the `Vagrantfile`.
```
Vagrant.configure("2") do |config|
  config.vm.box = "centos/7"
  config.vm.hostname = "server.example.com"
  config.vm.network "public_network"
  config.vm.provider "virtualbox" do |vb|
    vb.memory = "1024"
    vb.cpus = "2"
  end
end
```
This is a simple example of how we can assign a public network so that our Vagrant VM can be accessed by anyone.

We need to update the `config.vm.network` field as shown below.
```
config.vm.network "public_network"
```
This config will load the public IP address via DHCP.

Now, you can access your VM and check your assigned IP address using the following command: 
```
vagrant ssh
```

In this lesson, we'll learn about networking concepts in Vagrant and how to implement them.

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Networking With Vagrant

Networking

Private IP addresses

Public IP addresses

From	To
10.0.0.0	10.255.255.255
172.16.0.0	172.31.255.255
192.168.0.0	192.168.255.255