Buchtipps für IT Professionals (IT Themen werden aufgrund der Internationalität meist in englischer Sprache abgehandelt):

Anonymous Secure Access to Every Device or System

Available at DigitalBooks24 here

Anonymous Secure Access to Every Device or System

The professional way to overcome NAT, IPv4 and Firewalls!

No Port Forwarding Needed!

Works also through Proxy Servers and Firewalls denying all incoming!

A must read for all people involved in IoT (Internet of things), MQTT, remote support, device management and network and security support. Works on top of my Mosquitto Secure MQTT Setup and optionally using My own Certificate Authority too. These are described in other books. For sure the solution works for home users accessing their self hosted services too.
This book shows a perfect setup using real life examples. Works with virtual machines, cheap hardware or raspberry systems running Windows, Linux, Mac or Android.