How To Become A Hacker by Eric Steven Raymond

The Linux Command Line by William Shotts

The GNU Project

SSL/TLS related

The definitive guide to using the OpenSSL command line for configuration and testing, by Ivan Ristić:

https://www.feistyduck.com/books/openssl-cookbook/

If you're interested in going more in depth you can purchase BULLETPROOF TLS AND PKI by the same author.

BSD related links

A weekly podcast and "the place to B...SD":

https://www.bsdnow.tv/

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