DnsServer/Apps/AdvancedForwardingApp

Advanced Forwarding App

A DNS App for Technitium DNS Server that performs conditional forwarding to configured upstream resolvers.

Overview

• Conditional forwarding – route queries by domain and client network
• Multiple forwarders – define reusable upstream resolvers
• Proxy support – forwarders may use a proxy server definition
• Group-based control – forwarding rules are grouped by client network

Integration / extension points

• Implements: IDnsApplication, IDnsAuthoritativeRequestHandler, IDnsApplicationPreference
• Runs in the authoritative request path when forwarding is enabled.

Configuration

dnsApp.config contains these keys:

Property	Type	Default	Description
appPreference	number	200	App execution order.
enableForwarding	boolean	true	Master switch for forwarding.
proxyServers	array	[]	Proxy server definitions used by forwarders.
forwarders	array	[]	Forwarder definitions.
networkGroupMap	object	required	Maps client networks to group names.
groups	array	required	Forwarding groups and their domain/forwarder mappings.

Example

{
  "appPreference": 200,
  "enableForwarding": true,
  "proxyServers": [
    {
      "name": "local-proxy",
      "type": "socks5",
      "proxyAddress": "localhost",
      "proxyPort": 1080,
      "proxyUsername": null,
      "proxyPassword": null
    }
  ],
  "forwarders": [
    {
      "name": "quad9-doh",
      "proxy": null,
      "dnssecValidation": true,
      "forwarderProtocol": "Https",
      "forwarderAddresses": ["https://dns.quad9.net/dns-query (9.9.9.9)"]
    }
  ],
  "networkGroupMap": {
    "0.0.0.0/0": "everyone",
    "::/0": "everyone"
  },
  "groups": [
    {
      "name": "everyone",
      "enableForwarding": true,
      "forwardings": [
        {
          "forwarders": ["quad9-doh"],
          "domains": ["*"]
        }
      ]
    }
  ]
}

Runtime behavior

1. The app selects a client group based on networkGroupMap.
2. It checks whether forwarding is enabled for the selected group.
3. It matches the queried domain against the group's forwarding rules.
4. It returns custom FWD records for matching forwarders.

Risks / operational notes

• Overlapping forwarding rules can be hard to reason about.
• A bad upstream or proxy definition can break resolution for selected domains.
• Keep network group mappings explicit to avoid unintended routing.

Troubleshooting

• Confirm the client IP matches a group in networkGroupMap.
• Confirm the group has enableForwarding: true.
• Confirm the query domain matches one of the group's domains entries.