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

From Red Hat Enterprise Linux 6 Security Technical Implementation Guide

Associated with: CCI-001109

SV-50487r2_rule The systems local firewall must implement a deny-all, allow-by-exception policy for forwarded packets.

Vulnerability discussion

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.

Check content

Run the following command to ensure the default "FORWARD" policy is "DROP": # iptables -nvL | grep -i forward Chain FORWARD (policy DROP 0 packets, 0 bytes) If the default policy for the FORWARD chain is not set to DROP, this is a finding.

Fix text

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]

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