I'm trying to implement a very basic client firewall that allows ports 22 and 80 in and out, and DNS out on port 53 udp. I've followed along with several resources but can't seem to get DNS to work. To simplify the output a little I've left in SSH only, the following is the output of `iptables -L` after running my script:
Your current setup the first rule on INPUT is to allow all traffic in.
Your forward top rule is LOG everything being passed without actuall passing anything.
Wat is this device? Are you configuring a Linux box as a router/firewall?
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You would have a single rule as top rule allowing established and related traffic in without regard to the dport. From anywhere to anywhere on the INPUT.
The order of the rules should be arranged to minimize per packet evaluation.
Iptables can be use to protect the system or behave as a firewall to protect the network.
This outlines the flow chart of packets entering and exiting the system or a network.
Using chains I.e. a chaina in INPUT and FORWARD means you add a rule into chaina such as
-p tcp -m tcp -dport 22 -j ACCEPT
This will result in allowing an inbound ssh connection to enter (INPUT) and pass (FORWARD) to the service running on the system.
The other way you would need to add individual rules to each of the two tables.
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Your current setup the first rule on INPUT is to allow all traffic in.
Your forward top rule is LOG everything being passed without actuall passing anything.
Wat is this device? Are you configuring a Linux box as a router/firewall?
Look at fwbuilder.org