.. _quick-start:

###########
Quick Start
###########

This chapter will guide you on how to get up to speed quickly using your new
VyOS system. It will show you a very basic configuration example that will
provide a :ref:`nat` gateway for a device with two network interfaces
(`eth0` and `eth1`).

.. _quick-start-configuration-mode:

Configuration Mode
##################

By default, VyOS is in operational mode, and the command prompt displays a `$`.
To configure VyOS, you will need to enter configuration mode, resulting in the
command prompt displaying a `#`, as demonstrated below:

.. code-block:: none

  vyos@vyos$ configure
  vyos@vyos#

Commit and Save
################

After every configuration change, you need to apply the changes by using the
following command:

.. code-block:: none

  commit

Once your configuration works as expected, you can save it permanently by using
the following command:

.. code-block:: none

  save

Interface Configuration
#######################

* Your outside/WAN interface will be `eth0`. It will receive its interface
  address via DHCP.
* Your internal/LAN interface will be `eth1`. It will use a static IP address
  of `192.168.0.1/24`.

After switching to :ref:`quick-start-configuration-mode` issue the following
commands:

.. code-block:: none

  set interfaces ethernet eth0 address dhcp
  set interfaces ethernet eth0 description 'OUTSIDE'
  set interfaces ethernet eth1 address '192.168.0.1/24'
  set interfaces ethernet eth1 description 'INSIDE'


SSH Management
##############

After switching to :ref:`quick-start-configuration-mode` issue the following
commands, and your system will listen on every interface for incoming SSH
connections. You might want to check the :ref:`ssh` chapter on how to listen
on specific addresses only.

.. code-block:: none

  set service ssh port '22'


.. _dhcp-dns-quick-start:

DHCP/DNS quick-start
####################

The following settings will configure DHCP and DNS services on
your internal/LAN network, where VyOS will act as the default gateway and
DNS server.

* The default gateway and DNS recursor address will be `192.168.0.1/24`
* The address range `192.168.0.2/24 - 192.168.0.8/24` will be reserved for
  static assignments
* DHCP clients will be assigned IP addresses within the range of
  `192.168.0.9 - 192.168.0.254` and have a domain name of `internal-network`
* DHCP leases will hold for one day (86400 seconds)
* VyOS will serve as a full DNS recursor, replacing the need to utilize Google,
  Cloudflare, or other public DNS servers (which is good for privacy)
* Only hosts from your internal/LAN network can use the DNS recursor

.. code-block:: none

  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 default-router '192.168.0.1'
  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 name-server '192.168.0.1'
  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 domain-name 'vyos.net'
  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 lease '86400'
  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 range 0 start '192.168.0.9'
  set service dhcp-server shared-network-name LAN subnet 192.168.0.0/24 range 0 stop '192.168.0.254'

  set service dns forwarding cache-size '0'
  set service dns forwarding listen-address '192.168.0.1'
  set service dns forwarding allow-from '192.168.0.0/24'


NAT
###

The following settings will configure :ref:`source-nat` rules for our
internal/LAN network, allowing hosts to communicate through the outside/WAN
network via IP masquerade.

.. code-block:: none

  set nat source rule 100 outbound-interface name 'eth0'
  set nat source rule 100 source address '192.168.0.0/24'
  set nat source rule 100 translation address masquerade


Firewall
########

.. note:: Starting from VyOS 1.4-rolling-202308040557, a new firewall
   structure can be found on all vyos instalations. Documentation for most
   of the new firewall CLI can be found in the `firewall
   <https://docs.vyos.io/en/latest/configuration/firewall/general.html>`_
   chapter. The legacy firewall is still available for versions before
   1.4-rolling-202308040557 and can be found in the :ref:`legacy-firewall`
   chapter. The examples in this section use the new firewall configuration
   commands.

Add a set of firewall policies for our outside/WAN interface.

This configuration creates a proper stateful firewall that blocks all traffic
which was not initiated from the internal/LAN side first.

.. code-block:: none

  set firewall ipv4 forward filter default-action 'drop'
  set firewall ipv4 forward filter rule 10 action 'accept'
  set firewall ipv4 forward filter rule 10 state established 'enable'
  set firewall ipv4 forward filter rule 10 state related 'enable'
  set firewall ipv4 forward filter rule 20 action 'drop'
  set firewall ipv4 forward filter rule 20 state invalid 'enable'
  set firewall ipv4 forward filter rule 30 inbound-interface name 'eth1'
  set firewall ipv4 forward filter rule 30 action 'accept'

  set firewall ipv4 input filter default-action drop
  set firewall ipv4 input filter rule 10 action 'accept'
  set firewall ipv4 input filter rule 10 state established 'enable'
  set firewall ipv4 input filter rule 10 state related 'enable'
  set firewall ipv4 input filter rule 20 action 'drop'
  set firewall ipv4 input filter rule 20 state invalid 'enable'
  set firewall ipv4 input filter rule 30 action 'accept'
  set firewall ipv4 input filter rule 30 icmp type-name 'echo-request'
  set firewall ipv4 input filter rule 30 protocol 'icmp'
  set firewall ipv4 input filter rule 30 state new 'enable'

If you wanted to enable SSH access to your firewall from the outside/WAN
interface, you could create some additional rules to allow that kind of
traffic.

These rules allow SSH traffic and rate limit it to 4 requests per minute. This
blocks brute-forcing attempts:

.. code-block:: none

  set firewall ipv4 input filter rule 40 action 'drop'
  set firewall ipv4 input filter rule 40 inbound-interface name 'eth0'
  set firewall ipv4 input filter rule 40 destination port '22'
  set firewall ipv4 input filter rule 40 protocol 'tcp'
  set firewall ipv4 input filter rule 40 recent count '4'
  set firewall ipv4 input filter rule 40 recent time 'minute'
  set firewall ipv4 input filter rule 40 state new 'enable'

  set firewall ipv4 input filter rule 41 action 'accept'
  set firewall ipv4 input filter rule 41 destination port '22'
  set firewall ipv4 input filter rule 41 protocol 'tcp'
  set firewall ipv4 input filter rule 41 state new 'enable'


Commit changes, save the configuration, and exit configuration mode:

.. code-block:: none

  vyos@vyos# commit
  vyos@vyos# save
  Saving configuration to '/config/config.boot'...
  Done
  vyos@vyos# exit
  vyos@vyos$


Hardening
#########

Especially if you are allowing SSH remote access from the outside/WAN
interface, there are a few additional configuration steps that should be taken.

Replace the default `vyos` system user:

.. code-block:: none

  set system login user myvyosuser authentication plaintext-password mysecurepassword

Set up :ref:`ssh_key_based_authentication`:

.. code-block:: none

  set system login user myvyosuser authentication public-keys myusername@mydesktop type ssh-rsa
  set system login user myvyosuser authentication public-keys myusername@mydesktop key contents_of_id_rsa.pub

Finally, try and SSH into the VyOS install as your new user. Once you have
confirmed that your new user can access your router without a password, delete
the original ``vyos`` user and completely disable password authentication for
:ref:`ssh`:

.. code-block:: none

  delete system login user vyos
  set service ssh disable-password-authentication

As above, commit your changes, save the configuration, and exit
configuration mode:

.. code-block:: none

  vyos@vyos# commit
  vyos@vyos# save
  Saving configuration to '/config/config.boot'...
  Done
  vyos@vyos# exit
  vyos@vyos$

You now should have a simple yet secure and functioning router to experiment
with further. Enjoy!