4.3.3.1 Ensure ip6tables default deny firewall policy

Information

A default deny all policy on connections ensures that any unconfigured network usage will be rejected.

Note:

- Changing firewall settings while connected over network can result in being locked out of the system
- Remediation will only affect the active system firewall, be sure to configure the default policy in your firewall management to apply on boot as well

With a default accept policy the firewall will accept any packet that is not configured to be denied. It is easier to white list acceptable usage than to black list unacceptable usage.

Solution

IF IPv6 is enabled on your system:

Run the following commands to implement a default DROP policy:

# ip6tables -P INPUT DROP
# ip6tables -P OUTPUT DROP
# ip6tables -P FORWARD DROP

See Also

https://workbench.cisecurity.org/benchmarks/17074

Item Details

Category: SECURITY ASSESSMENT AND AUTHORIZATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|CA-9, 800-53|SC-7, 800-53|SC-7(5), CSCv7|9.4

Plugin: Unix

Control ID: 8108b9c5697521dd45e1ea2b8fda4b11e60089a3a508af9577fd71df1417d68b