IPTables

Some useful links to explain the concepts of IPTables

Concepts

• https://www.digitalocean.com/community/tutorials/what-is-a-firewall-and-how-does-it-work

• https://www.digitalocean.com/community/tutorials/how-the-iptables-firewall-works

• https://www.digitalocean.com/community/tutorials/how-to-choose-an-effective-firewall-policy-to-secure-your-servers

• http://www.thegeekstuff.com/2011/01/iptables-fundamentals/

• https://wiki.centos.org/HowTos/Network/IPTables

• https://iximiuz.com/en/posts/laymans-iptables-101/

Configuration

• http://fideloper.com/iptables-tutorial

• http://www.cyberciti.biz/tips/linux-iptables-examples.html

• http://www.thegeekstuff.com/2011/06/iptables-rules-examples

• https://linuxconfig.org/collection-of-basic-linux-firewall-iptables-rules

• http://blog.ls20.com/securing-your-server-using-ipset-and-dynamic-blocklists/

• http://www.cyberciti.biz/faq/how-do-i-block-an-ip-on-my-linux-server/

• http://www.tecmint.com/basic-guide-on-iptables-linux-firewall-tips-commands/

• http://www.cyberciti.biz/faq/rhel-fedorta-linux-iptables-firewall-configuration-tutorial/

• http://www.howtogeek.com/177621/the-beginners-guide-to-iptables-the-linux-firewall/

• https://www.digitalocean.com/community/tutorials/how-to-list-and-delete-iptables-firewall-rules

• https://www.digitalocean.com/community/tutorials/how-to-setup-a-basic-ip-tables-configuration-on-centos-6

• https://www.digitalocean.com/community/tutorials/7-security-measures-to-protect-your-servers

• https://www.frozentux.net/iptables-tutorial/chunkyhtml/x1309.html

• https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands

• https://jadendreamer.wordpress.com/2013/04/18/linux-tutorial-blocking-ip-addresses-from-your-server/

• http://www.linuxjournal.com/content/advanced-firewall-configurations-ipset

• https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7

• http://blog.nintechnet.com/how-to-block-w00tw00t-at-isc-sans-dfind-and-other-web-vulnerability-scanners/

Tuning and Hardening

• https://www.digitalocean.com/community/tutorials/how-to-test-your-firewall-configuration-with-nmap-and-tcpdump

IP Conntrack

• http://www.cyberciti.biz/faq/ip_conntrack-table-ful-dropping-packet-error/

• http://www.pc-freak.net/blog/resolving-nf_conntrack-table-full-dropping-packet-flood-message-in-dmesg-linux-kernel-log/

• http://blackbird.si/ip_conntrack-table-full-dropping-packet-conclusions-about-connection-tracking/

• https://www.scalescale.com/tips/nginx/ip_conntrack-table-full-dropping-packet/

• http://www.rigacci.org/wiki/lib/exe/fetch.php/doc/appunti/linux/sa/iptables/conntrack.html

• https://bobcares.com/blog/2011/04/21/ip-connection-tracking-ip_conntrack/

• https://timanovsky.wordpress.com/2009/04/10/tuning-linux-firewall-connection-tracker-ip_conntrack/