I am currently running a xubuntu 16.04.1 VM on VMWare using bridged networking. The end goal is to have only DNS and outgoing HTTP/HTTPS.
Iptables (latest version with iptables-persistent) is reacting strangely to commands. When I issue below, I have no connection, as expected.
-P INPUT DROP -P FORWARD DROP -P OUTPUT DROP COMMIT
When I issue localhost access and DNS, the firewall is open to all connections
-P INPUT DROP -P FORWARD DROP -P OUTPUT DROP -A OUTPUT -p udp --dport 53 -A INPUT -p udp --sport 53 COMMIT
Then when I run
iptables -F all connections are still allowed for a few minutes then I loose connection as before.
Ultimately, I'm wondering why the DNS and localhost rules are making the firewall fully open. Is everything routed through localhost?