https://www.packtpub.com/packt/offers/free-learning
(also seems to be posted on FB/PacktPub & /u/PacktStaff )

They seem to give away a free eBook daily, 'fyi'.
(need to register an email account; heavy js &cookies)

Most of their "4500+" items aren't specifically Linux tho.
They seem to publish a NEW book about every day!
(I bet anyone who can write, could author there)

I just legitimately got 9781782167105-LEARNING_LINUX_BINARY_ANALYSIS.pdf
(if I hilite the ISBN & right-click Search(Google) in Firefox, I get Amazon link at/near top result, to review or even "Look inside", to read bits of book)

Edit: today's: 9781783989522-MASTERING_WIRESHARK looks good!
(I think books can be just collected vs. downloaded/read 'now')
I missed May 1 9781784392536 Mastering Embedded Linux Programming & 4/19 Kali

Today: Practical Linux Security Cookbook 978-1785286421
(nice screenshots but 1-3yr old info; 0 Amazon reviews; no VPN; TCPwrappers)
5/13: 9781784394639-LEARNING_AWS (2yo; 'fair' per a few Amazon ratings)

p.s. UNrelated book(?) site I ran across: http://apprize.info/linux &a LPIC

Cool!

It's a Keeper!
Stuck in my VLG

Yes, a definite keeper! Thanks!

I'm posting today because of their popup (new today; 13hr left atm) that said:
"7 Days | 7 Best Titles campaign" (&because today is a Linux-specific title),
possibly meaning that tomorrow-Monday may have some interesting surprises.
(the past few weeks have had programming & miscellaneous topics; site shows covers of past 25)

Amazon link: (<1yo; 2reviews:5stars) 9781782168492-KALI_LINUX_2_WINDOWS_PENETRATION_TESTING

Note to anyone NEW to Kali: LQ -forbids- discussion of actual hacking; LQ&Kali -strongly- discourages use of Kali, except by "experienced professionals" (I've never messed with Kali; 1/17 .vdi here; book seems to use older Kali1.1 pre-systemd Deb7/Ubu14)

SO, forget Kali (maybe I shouldn't have posted this); let's see what tomorrow brings

p.s. UNrelated CC Linux101 books I ran across: https://www.tuxcademy.org/product/lxk1
Some non-free SysAdmin books I liked & posted about here.