Question is: What tools are best to use here to ensure I can sleep safely knowing no viruses, trojans, rootkits and other filth have nestled in my systems?
Also curious what are best, reliable websites to keep up-to-date on security best-practices related to this.
PS. I intend to start my scan with ClamAV, followed by chkrootkit and rkhunter as outlined here [2].
[0] https://youtube.com/watch?v=BGsw_l0tT10
[1] https://www.bleepingcomputer.com/news/security/lazarus-hackers-target-linux-windows-with-new-dacls-malware/
[2] https://www.linux.com/tutorials/security-tools-check-viruses-and-malware-linux/
Once you have clean system, you have to follow a discipline - do not work as root, restrict ssh access to specific users, don't run unnecessary services. Far too many to list here. Unfortunately, that is how the world is. Be paranoid. May be even use a VM to run software you don't trust. Always install software using package managers or at least do basic sanity checks like checksums on anything you download.
There is no software that will run a scan and give you a green check. If there is one like that, I wouldn't trust it either.