DHCP

AdGuard Home - DHCP Server

• Prerequisites
• Default Options
• Configuration
  • The dhcp.dhcpv4.options Array Field
  • DHCPv6 Options
• Automatic Hosts

AdGuard Home can be used as a DHCP server. This page describes how to do that.

Prerequisites

1. Make sure that you run an OS on which AdGuard Home supports DHCP. We currently don't support DHCP on Windows.

2. Make sure that your machine has a static IP address.

Default Options

By default, AdGuard Home will set itself as the DNS server for the DHCP clients. The default lease time is 24 hours.

Configuration

See the DHCP section in the configuration article for the overview of the DHCP configuration options. There are several configuration parameters for DHCP that can't be set via the AdGuard Home administrator dashboard. Those are described below.

The dhcp.dhcpv4.options Array Field

The options field accepts four types of values: hex, ip, ips, and text. They all start with the CODE, which MUST be an integer in the [1, 255] range. See also RFC 2132, sec. 3.

In accordance with RFC 2131, sec. 4.3.1, these options override the default options' values set by Adguard Home and requested by a client. Which means that if you want to set DNS server addresses using option 6, you should also add Adguard Home's own addresses there. Otherwise, AdGuard Home's filtering won't work for the DHCP clients who receive these DNS server addresses.

Option del has been added in v0.107.12. It is used to unconditionally remove options from the server's responses, which may lead to weird behaviors. Use with caution. On example where this option is useful is when a client doesn't accept a lease because of an option, see issue 4337.

• The hex format is:

  CODE hex HEX_VALUE
  

  For example, to set option 6, the DNS server, to two IP addresses, 1.2.3.4 and 1.2.3.5, use:

  # …
  'dhcp':
    # …
    'dhcpv4':
      # …
      'options':
      - '6 hex 0102030401020305'

• The ip format is:

  CODE ip IPV4_VALUE
  

  For example, to set option 6, the DNS server, to one IP address, 1.2.3.4, use:

  # …
  'dhcp':
    # …
    'dhcpv4':
      # …
      'options':
      - '6 ip 1.2.3.4'

• The ips format (since v0.106.0) is the same, but with comma-separated IP-addresses:

  # …
  'dhcp':
    # …
    'dhcpv4':
      # …
      'options':
      - '6 ips 1.2.3.4,5.6.7.8'

• The text format (since v0.106.0) allows you to put arbitrary UTF-8 text as the option data. For example:

  # …
  'dhcp':
    # …
    'dhcpv4':
      # …
      'options':
      - '252 text http://example.com'

• The del format (since v0.107.12) allows you to remove an option. For example:

  # …
  'dhcp':
    # …
    'dhcpv4':
      # …
      'options':
      - '61 del'

DHCPv6 Options

The option dhcp.dhcpv6.ra_slaac_only, if true, sends RA packets forcing the clients to use SLAAC. The DHCPv6 server won't be started in this case.

The option dhcp.dhcpv6.ra_allow_slaac, if true, sends RA packets allowing the clients to choose between SLAAC and DHCPv6.

Automatic Hosts

Machines in the network can be reached more easily using the hostnames they send in the DHCP requests with a configurable top-level domain (TLD). By default, the TLD is lan. For example, if you have a machine called “workstation” in the network, and it sends a DHCP request with option 12 set to workstation, you can reach it over HTTP on the host http://workstation.lan.

You can also set a custom TLD or domain name using the dns.local_domain_name field in the configuration file.