05_08_09_PLUGIN_EDNS0OPT.md

EDNS0 Options Plugin

edns0opt lets you add arbitrary EDNS0 options to outgoing queries. It stores the options in the context metadata so that forwarders can include them in upstream requests.

Arguments

• options: sequence of { code: <number>, data: [<byte>, ...] }: the option code and raw bytes.
• preserve_existing (boolean): whether to preserve existing EDNS0 options (default: true).

Example

plugins:
  - type: edns0opt
    args:
      options:
        - code: 8
          data: [0, 1, 24, 0, 192, 168, 1]
      preserve_existing: false

Behavior

• Stores EDNS0 options in metadata key edns0_options for downstream consumption.
• Useful for adding ECS, cookies, or other EDNS0 extensions without modifying forwarding code.