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RustProxy/docs/NOT_FOUND_HOSTS.md
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2026-10-17 11:57:16 +02:00

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Local-response / 404 hosts

RustProxy 0.22.3 has a dedicated 404 hosts page for domains that should be owned by RustProxy but must not contact a backend.

Each entry has the same frontend model as vhosts/redirects:

  • one or more hostnames,
  • named listener selection,
  • optional TLS certificate,
  • independent HTTP/2 and HTTP/3 switches.

The response can be:

  • the built-in RustProxy is running placeholder,
  • an application-style built-in status page for 401, 403, 404, 429, 503 or 504,
  • an empty/status-only response,
  • bounded custom HTML.

The status is selected rather than typed manually. Application-style pages use the bundled 400/401/403/404/408/410/413/429/500/502/503/504 templates. Placeholder, empty and custom-HTML modes expose the supported application error set: 400/401/403/404/408/413/429/500/502/503/504. HTTP/2 and HTTP/3 toggles are shown beside the listener controls because they apply to the selected frontend listeners. Host/listener ownership is validated against vhosts and redirect hosts, so two active configuration objects cannot claim the same frontend binding.

All 404-host responses remain local and never open an upstream connection. They are not stored in RustProxy cache. Before the response leaves RustProxy, cache policy/validator headers and RustProxy X-Cache* diagnostics are removed, so 404 hosts do not advertise cache behavior on the wire. The built-in RustProxy is running placeholder also intentionally omits optional RustProxy server, diagnostic, security, compression and backend headers.