"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them (the full list is here):
W. Richard Stevens
For students writing applications that run over TCP/IP, or for those responsible for managing and maintaining a TCP/IP internet, this book's innovative approach helps readers at all levels to truly understand how TCP/IP really works. Rather than just describing the protocols from an abstract, standards-related point of view-describing what the standards say the protocol suite should do-TCP/IP Illustrated, Volume 1 actually shows the protocols in action. Stevens also recognizes that readers deal with multiple TCP/IP implementations on heterogeneous platforms. Therefore, the examples in this book show how current, popular TCP/IP implementations operate-SunOS 4.1.3, Solaris 2.2, System V Release 4, BSD/386, AIX 3.2.2, and 4.4 BSD-and they relate these real-world implementations to the RFC standards.