We propose several "tracks" for readers with different interests and skills:
Chapters 3,4-5 and 10 are the most important for understanding SSH and how to build and configure servers. However, as the administrator of a security product, you should read the whole book.
Chapters 1 and 2 provide an overview, and Chapters 6,7,8-9 discuss SSH clients in depth.
Read Chapters 1, 2, 13, 14, and 16,17-18 for starters, and then others as your interests guide you.
Read Chapters 1, 2, 13, and 15 for starters, and then others as your interests guide you.
Read Chapters 1, 2, and 13 for starters, and then others as your interests guide you.
Even if you are experienced with SSH, you'll likely find value in Chapters 3,4,5,6,7,8,9,10,11-12. We cover significant details the Unix manpages leave unclear or unmentioned, including major concepts, compile-time flags, server configuration, and forwarding.