Since there are several approaches on solving authentication and authorization in distributed web applications Spring Boot Admin doesn't ship a default one.
However you can include Spring Security to your Spring Boot Admin Server and configure it the way you like.
=== Securing Client's Actuator Endpoints ===
The simplest way to secure your actuator endpoints is to use basic authorization and the same username/password for all applications. This way the browser asks for the credentials and if you set `zuul.senstivieHeaders:` the Zuul Proxy in Spring Boot Admin Server forwards them to the clients.
For more complex solutions (Spring Session, OAuth2, ...) please have a look at the samples in https://github.com/joshiste/spring-boot-admin-samples[joshiste/spring-boot-admin-samples^].