https://nalar.dev/tags/trust-boundary/ Recent content in Trust Boundary on Nalar Hugo en-us Sun, 20 Sep 2026 00:00:00 +0000 https://nalar.dev/trust-forwarded-headers-only-from-known-proxies/ Sun, 20 Sep 2026 00:00:00 +0000 https://nalar.dev/trust-forwarded-headers-only-from-known-proxies/ <h1 id="trust-forwarded-headers-only-from-known-proxies">Trust Forwarded Headers Only from Known Proxies</h1> <p>A reverse proxy often knows facts that an application server cannot observe directly. It may terminate TLS, accept the public hostname, and receive the client connection before opening a separate connection to the backend. Forwarding fields carry those facts across the second hop.</p> <p>That arrangement is safe only when the backend can distinguish proxy-supplied metadata from client-supplied HTTP fields. A header name does not create trust. The trust comes from the network path, the proxy configuration, and a rule that defines which hop may set or replace each field.</p>