Lắp Đặt Internet FPT Quảng Ninh

[TrevorH]

You forgot to tell us the error message.

I am guessing that you're getting an error like "bash: iptables: command not found" and the most common reason for this is if you have become root the wrong way. If you just run su then you get root's powers but not their environment - specifically their PATH is not set up. You need to run su - and that minus sign is important as it makes su set you up like you had logged in as root with their environment set correctly. The PATH then includes all the sbin directories and then it'll find iptables.