My second question is about iptables. I have it installed, but it's not working. The tutorials I read suggest that there is a file called /sbin/iptables, but no such file exists. When I create it, add ...

Iptables, more properly referred to as “iptables/netfilter” because of the two modules that are involved — the userspace module “iptables” and the kernel ...

iptables is the user-space tool for configuring firewall rules in the Linux kernel. It is actually a part of the larger netfilter framework. Perhaps because iptables is the most visible part of the ...