iptables

IPTables for CentOS

Whenever you get a new RedHat or CentOS instance you want to secure it by setting up firewall rules using the builtin in iptables. If you spinoff an Amazon EC2 instance then you'd be doing the equivalent using Security Groups, which are a slightly higher level concept but essentially performs the same function. If running a VPS on barebones CentOS, iptables is the easiest option. Word of Caution: Its easy to lock yourself out of the system if you make a mistake when configuring iptables. I prefer writing all the rules in a script file, double checking the commands to make sure I'm not closing SSH on port 22. Also, its a good idea to remain logged in the current SSH shell after executing iptables rules and then attempt to login in a new SSH shell to ensure you still have access to the s…