[[http]]
= HTTP

All HTTP-based communication, including https://www.troyhunt.com/heres-why-your-static-website-needs-https/[static resources], should be protected by https://cheatsheetseries.owasp.org/cheatsheets/Transport_Layer_Protection_Cheat_Sheet.html[using TLS].

As a framework, Spring Security does not handle HTTP connections and thus does not provide support for HTTPS directly.
However, it does provide a number of features that help with HTTPS usage.

[[http-redirect]]
== Redirect to HTTPS

When a client uses HTTP, you can configure Spring Security to redirect to HTTPS in both xref:servlet/exploits/http.adoc#servlet-http-redirect[Servlet] and xref:reactive/exploits/http.adoc#webflux-http-redirect[WebFlux] environments.

[[http-hsts]]
== Strict Transport Security

Spring Security provides support for xref:features/exploits/headers.adoc#headers-hsts[Strict Transport Security] and enables it by default.

[[http-proxy-server]]
== Proxy Server Configuration

When using a proxy server, it is important to ensure that you have configured your application properly.
For example, many applications have a load balancer that responds to request for `\https://example.com/` by forwarding the request to an application server at `\https://192.168.0.107`
Without proper configuration, the application server can not know that the load balancer exists and treats the request as though `\https://192.168.0.107:8080` was requested by the client.

To fix this, you can use https://tools.ietf.org/html/rfc7239[RFC 7239] to specify that a load balancer is being used.
To make the application aware of this, you need to configure your application server to be aware of the X-Forwarded headers.
For example, Tomcat uses https://tomcat.apache.org/tomcat-10.1-doc/api/org/apache/catalina/valves/RemoteIpValve.html[`RemoteIpValve`] and Jetty uses https://eclipse.dev/jetty/javadoc/jetty-11/org/eclipse/jetty/server/ForwardedRequestCustomizer.html[`ForwardedRequestCustomizer`].
Alternatively, Spring users can use https://docs.spring.io/spring-framework/reference/web/webmvc/filters.html#filters-forwarded-headers[`ForwardedHeaderFilter`] with the Servlet stack or https://docs.spring.io/spring-framework/reference/web/webflux/reactive-spring.html#webflux-forwarded-headers[`ForwardedHeaderTransformer`] with the Reactive stack.

Spring Boot users can use the `server.forward-headers-strategy` property to configure the application.
See the https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto.webserver.use-behind-a-proxy-server[Spring Boot documentation] for further details.
