Security# Some useful links to explain the concepts of Security in Linux OS Concepts# imthenachoman/How-To-Secure-A-Linux-Server https://dev.to/danlebrero/kerberos-explained-in-pictures https://technically.substack.com/p/how-does-authentication-work Rootkits# https://www.digitalocean.com/community/tutorials/how-to-use-rkhunter-to-guard-against-rootkits-on-an-ubuntu-vps https://www.woktron.com/secure/knowledgebase/79/Installation-Rootkit-Hunter-rkhunter-on-CentOS-5-and-6.html https://www.tecmint.com/install-rootkit-hunter-scan-for-rootkits-backdoors-in-linux/ Fail2Ban# https://www.digitalocean.com/community/tutorials/how-to-protect-ssh-with-fail2ban-on-centos-6 https://www.digitalocean.com/community/tutorials/how-fail2ban-works-to-protect-services-on-a-linux-server https://www.tecmint.com/use-fail2ban-to-secure-linux-server/ https://www.the-art-of-web.com/system/fail2ban-log/ https://www.dghost.com/techno/internet/the-power-of-fail2ban fail2ban/fail2ban https://aarvik.dk/prevent-intrusion-with-fail2ban/ TCP Wrappers# https://static.closedsrc.org/articles/dn-articles/hosts_allow.html https://www.tecmint.com/secure-linux-tcp-wrappers-hosts-allow-deny-restrict-access/ https://www.cyberciti.biz/faq/tcp-wrappers-hosts-allow-deny-tutorial/ https://grsecurity.net/index GPG# https://yanhan.github.io/posts/2017-09-27-how-to-use-gpg-to-encrypt-stuff/ https://inspirezone.tech/using-gpg-keys-on-github/ https://smarttech101.com/how-to-encrypt-and-sign-your-files-using-gpg/ SELinux# Concepts of SELinux# https://www.digitalocean.com/community/tutorial_series/an-introduction-to-selinux-on-centos-7 https://www.revsys.com/writings/quicktips/turn-off-selinux.html DDoS# https://www.digitalattackmap.com/understanding-ddos/ https://blog.cloudflare.com/the-ddos-that-almost-broke-the-internet/ https://www.incapsula.com/ddos/ddos-attacks/ Configuration# https://mkyong.com/linux/how-to-block-attackers-ip-with-null-route-command/ https://www.opensourceforu.com/2011/04/securing-apache-part-8-dos-ddos-attacks/ https://developers.google.com/speed/public-dns/docs/security#introduction-dns-security-threats-and-mitigations http://www.tldp.org/HOWTO/Firewall-Piercing/index.html https://www.ubuntufree.com/how-to-stop-a-ddos-attack-on-ubuntu/ aquasecurity/trivy https://www.checkov.io/