Add separate section in "features" docs on Security

Lists all the basic autoconfig defaults and quick pointers on
how to change or disable.

Fixes gh-514

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -1102,23 +1102,6 @@ Look at {sc-spring-boot-actuator}/autoconfigure/ErrorMvcAutoConfiguration.{sc-ex
 == Security
 
 
-
-[[howto-secure-an-application]]
-=== Secure an application
-If Spring Security is on the classpath then web applications will be secure by default
-(``basic'' authentication on all endpoints) . To add method-level security to a web
-application you can simply `@EnableGlobalMethodSecurity` with your desired settings.
-Additional information can be found in the {spring-security-reference}#jc-method[Spring
-Security Reference].
-
-The default `AuthenticationManager` has a single user (username ``user'' and password
-random, printed at INFO level when the application starts up). You can change the
-password by providing a `security.user.password`. This and other useful properties
-are externalized via
-{sc-spring-boot-autoconfigure}/security/SecurityProperties.{sc-ext}[`SecurityProperties`].
-
-
-
 [[howto-switch-off-spring-boot-security-configuration]]
 === Switch off the Spring Boot security configuration
 If you define a `@Configuration` with `@EnableWebSecurity` anywhere in your application
@@ -1157,7 +1140,9 @@ use this in a webapp is to inject it into a void method in a
 	}
 ----
 
-
+You will get the best results if you put this in a nested class, or a standalone class (i.e.
+not mixed in with a lot of other `@Beans` that might be allowed to influence the order of
+instantiation). The https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples/spring-boot-sample-web-secure[secure web sample] is a useful template to follow.
 
 [[howto-enable-https]]
 === Enable HTTPS

spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -251,9 +251,9 @@ all non-sensitive endpoints to be exposed over HTTP. The default convention is t
 
 [[production-ready-sensitive-endpoints]]
 === Exposing sensitive endpoints
-If you use ``Spring Security'' sensitive endpoints will also be exposed over HTTP. By
+If you use ``Spring Security'' sensitive endpoints will be exposed over HTTP, but also 
-default ``basic'' authentication will be used with the username `user` and a generated
+protected. By default ``basic'' authentication will be used with the username `user` 
-password.
+and a generated password (which is printed on the console when the application starts).
 
 TIP: Generated passwords are logged as the application starts. Search for ``Using default
 password for application endpoints''.

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -993,7 +993,66 @@ packaged as an executable archive), there are some limitations in the JSP suppor
 There is a {github-code}/spring-boot-samples/spring-boot-sample-web-jsp[JSP sample] so
 you can see how to set things up.
 
+[[boot-features-security]]
+== Security
+If Spring Security is on the classpath then web applications will be secure by default
+with ``basic'' authentication on all HTTP endpoints. To add method-level security to a web
+application you can also add `@EnableGlobalMethodSecurity` with your desired settings.
+Additional information can be found in the {spring-security-reference}#jc-method[Spring
+Security Reference].
 
+The default `AuthenticationManager` has a single user (username
+``user'' and password random, printed at INFO level when the
+application starts up). You can change the password by providing a
+`security.user.password`. This and other useful properties are
+externalized via
+{sc-spring-boot-autoconfigure}/security/SecurityProperties.{sc-ext}[`SecurityProperties`]
+(properties prefix "security").
+
+The default security configuration is implemented in
+`SecurityAutoConfiguration` and in the classes imported from there
+(`SpringBootWebSecurityConfiguration` for web security and
+`AuthenticationManagerConfiguration` for authentication configuration
+which is also relevant in non-web applications). To switch off the
+Boot default configuration completely in a web application you can add
+a bean with `@EnableWebSecurity`. To customize it you normally use
+external properties and beans of type `WebConfigurerAdapter` (e.g. to
+add form-based login). There are several secure applications in the
+{github-code}/spring-boot-samples/[Spring Boot samples] to get you
+started with common use cases.
+
+The basic features you get out of the box in a web application are
+
+* An `AuthenticationManager` bean with in-memory store and a single
+  user (see `SecurityProperties.User` for the properties of the user).
+
+* Ignored (unsecure) paths for common static resource locations
+  (`/css/**`, `/js/**`, `/images/**` and `**/favicon.ico`).
+
+* HTTP Basic security for all other endpoints.
+
+* Security events published to Spring's `ApplicationEventPublisher`
+  (successful and unsuccessful authentication and access denied).
+
+* Common low-level features (HSTS, XSS, CSRF, caching) provided by Spring
+Security are on by default.
+
+All of the above can be switched on and off or modified using external
+properties (`security.*`).
+
+If the Actuator is also in use, you will find:
+
+* The management endpoints are secure even if the application
+  endpoints are unsecure.
+
+* Security events are transformed into `AuditEvents` and published to
+  the `AuditService`.
+
+* The default user will have the "ADMIN" role as well as the "USER"
+  role.
+
+The Actuator security features can be modified using external
+properties (`management.security.*`).
 
 [[boot-features-sql]]
 == Working with SQL databases