path: root/docs/configuration/service/dhcp-server.rst

DHCP Server
-----------

Multiple DHCP Servers can be run from a single machine. Each DHCP service is
identified by a `shared-network-name`.

DHCP Server Example
^^^^^^^^^^^^^^^^^^^

In this example, we are offering address space in the 172.16.17.0/24 network,
which is on eth1, and pppoe0 is our connection to the internet. We are using
the network name `dhcpexample`.

Prerequisites
^^^^^^^^^^^^^

Configuring the PPPoE interface is assumed to be done already, and appears
on `pppoe0`

Interface Configuration
^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: none

 set interface ethernet eth1 address 172.16.17.1/24

Multiple ranges can be defined and can contain holes.

.. code-block:: none

  set service dhcp-server shared-network-name dhcpexample authoritative
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 default-router 172.16.17.1
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 dns-server 172.16.17.1
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 lease 86400
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 range 0 start 172.16.17.100
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 range 0 stop 172.16.17.199


Explanation
^^^^^^^^^^^

* :code:`set service dhcp-server shared-network-name dhcpexample authoritative`

  This says that this device is the only DHCP server for this network. If other
  devices are trying to offer DHCP leases, this machine will send 'DHCPNAK' to
  any device trying to request an IP address that is
  not valid for this network.

* :code:`set service dhcp-server shared-network-name dhcpexample subnet
  172.16.17.0/24 default-router 172.16.17.1`

  This is a configuration parameter for the subnet, saying that as part of the
  response, tell the client that I am the default router for this network

* :code:`set service dhcp-server shared-network-name dhcpexample subnet
  172.16.17.0/24 dns-server 172.16.17.1`

  This is a configuration parameter for the subnet, saying that as part of the
  response, tell the client that I am the DNS server for this network. If you
  do not want to run a DNS server, you could also provide one of the public
  DNS servers, such as google's. You can add multiple entries by repeating the
  line.

* :code:`set service dhcp-server shared-network-name dhcpexample subnet
  172.16.17.0/24 lease 86400`

  Assign the IP address to this machine for 24 hours. It is unlikely you'd need
  to shorten this period, unless you are running a network with lots of devices
  appearing and disappearing.


* :code:`set service dhcp-server shared-network-name dhcpexample subnet
  172.16.17.0/24 range 0 start 172.16.17.100`

  Make a range of addresses available for clients starting from .100 [...]

* :code:`set service dhcp-server shared-network-name dhcpexample subnet
  172.16.17.0/24 range 0 stop 172.16.17.199`

  [...] and ending at .199


Failover
^^^^^^^^

VyOS provides support for DHCP failover:

.. code-block:: none

  set service dhcp-server shared-network-name 'LAN' subnet '192.168.0.0/24' failover local-address '192.168.0.1'
  set service dhcp-server shared-network-name 'LAN' subnet '192.168.0.0/24' failover name 'foo'
  set service dhcp-server shared-network-name 'LAN' subnet '192.168.0.0/24' failover peer-address '192.168.0.2'

.. note:: `name` must be identical on both sides!

The primary and secondary statements determines whether the server is
primary or secondary

.. code-block:: none

  set service dhcp-server shared-network-name 'LAN' subnet '192.168.0.0/24' failover status 'primary'

or

.. code-block:: none

  set service dhcp-server shared-network-name 'LAN' subnet '192.168.0.0/24' failover status 'secondary'

.. note:: In order for the primary and the secondary DHCP server to keep
   their lease tables in sync, they must be able to reach each other on TCP
   port 647. If you have firewall rules in effect, adjust them accordingly.

Static mappings MAC/IP
^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: none

  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 static-mapping static-mapping-01 ip-address 172.16.17.10
  set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 static-mapping static-mapping-01 mac-address ff:ff:ff:ff:ff:ff

DHCP server options
^^^^^^^^^^^^^^^^^^^^^^^^^

default-router (DHCP option 003)
  :code:`set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 default-router <ROUTER-IP>`

dns-server (DHCP option 006)
  :code:`set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 dns-server <DNS-SERVER-IP>`

domain-name  Client domain name (DHCP option 015)
  :code:`set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 domain-name "<DOMAIN-NAME>"`

domain-search (DHCP option 119)
  This option can be given multiple times if you need multiple search domains
  :code:`set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 domain-search "<DOMAIN_NAME_1>"`
  :code:`set service dhcp-server shared-network-name dhcpexample subnet 172.16.17.0/24 domain-search "<DOMAIN_NAME_2>"`



DHCPv6 server
-------------

VyOS provides DHCPv6 server functionality which is described in this section.
In order to use the DHCPv6 server it has to be enabled first:

.. code-block:: none

  set service dhcpv6-server

To restart the DHCPv6 server (operational mode):

.. code-block:: none

  restart dhcpv6 server

To show the current status of the DHCPv6 server use:

.. code-block:: none

  show dhcpv6 server status

Show statuses of all assigned leases:

.. code-block:: none

  show dhcpv6 server leases

DHCPv6 server options
^^^^^^^^^^^^^^^^^^^^^

DHCPv6 server preference value
******************************

Clients receiving advertise messages from multiple servers choose the server
with the highest preference value. The range for this value is `0...255`. Set
a preference value for the DHCPv6 server:

.. code-block:: none

  set service dhcpv6-server preference <preference value>

Delete a preference:

.. code-block:: none

  set service dhcpv6-server preference

Show current preference:

.. code-block:: none

  show service dhcpv6-server preference

Specify address lease time
**************************

The default lease time for DHCPv6 leases is 24 hours. This can be changed by
supplying a `default-time`, `maximum-time` and `minimum-time` (all values in
seconds):

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> lease-time {default <default-time> | maximum <maximum-time> | minimum <minimum-time>}

Reset the custom lease times:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> lease-time {default | maximum | minimum}

Show the current configuration:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> lease-time {default | maximum | minimum}

Specify NIS domain
******************

A Network Information (NIS) domain can be set to be used for DHCPv6 clients:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-domain <nis-domain-name>

To Delete the NIS domain:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-domain <nis-domain-name>

Show a configured NIS domain:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-domain <nis-domain-name>

Specify NIS+ domain
*******************

The procedure to specify a Network Information Service Plus (NIS+) domain is
similar to the NIS domain one:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-domain <nisplus-domain-name>

To Delete the NIS+ domain:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-domain <nisplus-domain-name>

Show a configured NIS domain:

 # show service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-domain <nisplus-domain-name>

Specify NIS server address
**************************

To specify a NIS server address for DHCPv6 clients:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-server <IPv6 address>

Delete a specified NIS server address:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-server <IPv6 address>

Show specified NIS server addresses:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> nis-server

Specify NIS+ server address
***************************

To specify a NIS+ server address for DHCPv6 clients:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-server <IPv6 address>

Delete a specified NIS+ server address:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-server <IPv6 address>

Show specified NIS+ server addresses:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> nisplus-server

Specify a SIP server address for DHCPv6 clients
***********************************************

By IPv6 address
###############


A Session Initiation Protocol (SIP) server address can be specified
for DHCPv6 clients:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-address <IPv6 address>

Delete a specified SIP server address:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-address <IPv6 address>

Show specified SIP server addresses:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-address

By FQDN
#######

A name for SIP server can be specified:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-name <sip-server-name>

Delete a specified SIP server name:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-name <sip-server-name>

Show specified SIP server names:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> sip-server-name

Simple Network Time Protocol (SNTP) server address for DHCPv6 clients
*********************************************************************

A SNTP server address can be specified for DHCPv6 clients:

.. code-block:: none

  set service dhcpv6-server shared-network-name <name> subnet <ipv6net> sntp-server-address <IPv6 address>

Delete a specified SNTP server address:

.. code-block:: none

  delete service dhcpv6-server shared-network-name <name> subnet <ipv6net> sntp-server-address <IPv6 address>

Show specified SNTP server addresses:

.. code-block:: none

  show service dhcpv6-server shared-network-name <name> subnet <ipv6net> sntp-server-address

DHCPv6 address pools
^^^^^^^^^^^^^^^^^^^^

DHCPv6 address pools must be configured for the system to act as a DHCPv6
server. The following example describes a common scenario.

Example 1: DHCPv6 address pool
******************************

A shared network named `NET1` serves subnet `2001:db8:100::/64` which is
connected to `eth1`, a DNS server at `2001:db8:111::111` is used for name
services. The range of the address pool shall be `::100` through `::199`. The
lease time will be left at the default value which is 24 hours.

.. code-block:: none

  set service dhcpv6-server shared-network-name NET1 subnet 2001:db8:100::/64 address-range start 2001:db8:100::100 stop 2001:db8:100::199
  set service dhcpv6-server shared-network-name NET1 subnet 2001:db8:100::/64 name-server 2001:db8:111::111

Commit the changes and show the configuration:

.. code-block:: none

  commit
  show service dhcpv6-server
      shared-network-name NET1 {
          subnet 2001:db8:100::/64 {
             address-range {
                start 2001:db8:100::100 {
                   stop 2001:db8:100::199
                }
             }
             name-server 2001:db8:111::111
          }
      }

Static mappings
^^^^^^^^^^^^^^^

In order to map specific IPv6 addresses to specific hosts static mappings can
be created. The following example explains the process.

Example 1: Static IPv6 MAC-based mapping
****************************************

IPv6 address `2001:db8:100::101` shall be statically mapped to a device with
MAC address `00:15:c5:b7:5e:23`, this host-specific mapping shall be named
`client1`.

.. note:: The MAC address identifier is defined by the last 4 byte of the
   MAC address.

.. code-block:: none

  set service dhcpv6-server shared-network-name NET1 subnet 2001:db8:100::/64 static-mapping client1 ipv6-address 2001:db8:100::101
  set service dhcpv6-server shared-network-name NET1 subnet 2001:db8:100::/64 static-mapping client1 identifier c5b75e23

Commit the changes and show the configuration:

.. code-block:: none

  show service dhcp-server shared-network-name NET1
     shared-network-name NET1 {
         subnet 2001:db8:100::/64 {
            name-server 2001:db8:111::111
            address-range {
                start 2001:db8:100::100 {
                   stop 2001:db8:100::199 {
                }
            }
            static-mapping client1 {
               ipv6-address 2001:db8:100::101
               identifier c5b75e23
            }
         }
      }