The systems local firewall must implement a deny-all, allow-by-exception policy for forwarded packets.

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The systems local firewall must implement a deny-all, allow-by-exception policy for forwarded packets.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38686	RHEL-06-000320	SV-50487r1_rule		Medium

Description
In "iptables" the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to "DROP" implements proper design for a firewall, i.e., any packets which are not explicitly permitted should not be accepted.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2017-05-19

Details

Check Text ( C-46248r1_chk )
Run the following command to ensure the default "FORWARD" policy is "DROP": grep ":FORWARD" /etc/sysconfig/iptables The output must be the following: # grep ":FORWARD" /etc/sysconfig/iptables :FORWARD DROP [0:0] If it is not, this is a finding.

Fix Text (F-43635r1_fix)
To set the default policy to DROP (instead of ACCEPT) for the built-in FORWARD chain which processes packets that will be forwarded from one interface to another, add or correct the following line in "/etc/sysconfig/iptables": :FORWARD DROP [0:0]