I'm using CentOS. What I'm wondering is, what happens if I manually edit /etc/sysconfig/iptables and save it? Is that the definitive source? When I type iptables -L I get something that doesn't match the contents of that file. Is there a way I can just edit the chains directly without adding/removing rules one at a time? i.e. open VIM and get everything set up the way I want it and then save. Along those lines, when I do something like iptables -A INPUT , where does that go in the immediate sense? Is it not applied until I do an iptables-save? I feel like I'm just missing an a-ha moment here and I can't seem to find the answer in a search.