Yesterday I installed Cent OS 6 and had to flush the default IPtables rules (IPtables -F) in order to access a web app via my browser.
Having very little experience with Linux/Network security this got me thinking about how open to attack I am with the rules flushed.
I know/assume/hope my router has a firewall which protects me from attackers on the wider PDN (i.e. internet).
But I am wondering am I now wide open to attack if someone plugs directly into my LAN?
Also, even with an effective IPtables rule strategy can I still succumb to attack, does the firewall perform all blocks/permits/redirects when packets arrive at the NIC or do they proceed past the NIC onto the CPU before the being accessed against the IPtables rules?