Ensure IPv6 loopback traffic is configured

LowLevel 2Automatedbottlerocket

Description

Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network (::1). The audit runs ip6tables -S and requires the INPUT lo ACCEPT, INPUT ::1 DROP and OUTPUT lo ACCEPT rules (rule order is not verified). Run tmaegis on the host through the admin container root shell (sudo sheltie).

How it is checked

Audit method: Shell command

shell

in=$(ip6tables -S INPUT 2>/dev/null) || exit 1
out=$(ip6tables -S OUTPUT 2>/dev/null) || exit 1
bad=0
printf '%s\n' "$in" | grep -Eq -- '^-A INPUT -i lo( .*)? -j ACCEPT' || { echo 'missing: -A INPUT -i lo -j ACCEPT'; bad=1; }
printf '%s\n' "$in" | grep -Eq -- '^-A INPUT -s ::1(/128)?( .*)? -j DROP' || { echo 'missing: -A INPUT -s ::1(/128)? -j DROP'; bad=1; }
printf '%s\n' "$out" | grep -Eq -- '^-A OUTPUT -o lo( .*)? -j ACCEPT' || { echo 'missing: -A OUTPUT -o lo -j ACCEPT'; bad=1; }
[ "$bad" -eq 0 ] && echo compliant

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Run the following commands to implement the loopback rules: # ip6tables -A INPUT -i lo -j ACCEPT # ip6tables -A OUTPUT -o lo -j ACCEPT # ip6tables -A INPUT -s ::1 -j DROP

Properties

Operating systems: Any
Tags: bottlerocketnetwork
Reference: CIS Bottlerocket Benchmark v1.0.0 - 3.4.2.2 Ensure IPv6 loopback traffic is configured

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target bottlerocket --level 2