DHCP relay

DHCP Relay provides a way for DHCP clients to communicate with DHCP servers that are not available on the same local subnet/broadcast domain. When you enable DHCP Relay, Magic WAN Connector forwards DHCP discover messages to a predefined DHCP server, and routes the responses back to the original device that sent the discover message.

flowchart LR
accTitle: An example of Connector in DHCP Relay mode
    a(Magic WAN Connector) --> b(Internet) --> c(DHCP server)

    subgraph Customer site
    d[LAN 1] <--> a
    e[LAN 2] <--> a
    end

    c --> a
    classDef orange fill:#f48120,color: black
    class a orange

The above graph shows Connector sending DHCP discover messages to a DHCP server offsite.

To configure DHCP relay:

Dashboard

1. Log in to the Cloudflare dashboard ↗ and select your account.
2. Go to Magic WAN > Sites.
3. Select your site > Edit.
4. Select Network.
5. In LAN configuration, select the LAN where you need to configure DHCP relay.
6. Select Edit.
7. Select This is a DHCP Relay.
8. In Upstream DHCP server addresses, enter the IP address of your DHCP server.
9. (Optional) If you need to add more DHCP server addresses, select Add upstream DHCP server address as many times as needed, and enter the new values.

API

Note

You will need your account ID and API Key to use the API.

Create a PUT request to update the LAN where you want to enable DHCP relay:

Example:

curl --request PUT \
https://api.cloudflare.com/client/v4/accounts/{account_id}/magic/sites/{site_id}/lans/{lan_id} \
--header "X-Auth-Email: <EMAIL>" \
--header "X-Auth-Key: <API_KEY>" \
--header "Content-Type: application/json" \
--data '{
  "lan": {
    "static_addressing": {
      "dhcp_relay": {
        "server_addresses": [
          "192.0.2.1"
        ]
      }
    }
  }
}'