SV-37930r2: The system must not have IP forwarding for IPv6 enabled, unless the system is an IPv6 router. | Red Hat Enterprise Linux 5 Security Technical Implementation Guide

Loading benchmark…

Assessment Title

Rule Text

The system must not have IP forwarding for IPv6 enabled, unless the system is an IPv6 router.

Description

Discussion Text

If the system is configured for IP forwarding and is not a designated router, it could be used to bypass network security by providing a path for communication not filtered by network devices.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000366

Additional Details

Responsibility

System Administrator

References

DPMS Target Red Hat 5 DISA DPMS Target Red Hat 5 2154

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.fso.rhel11:def:364
# The system must not have IP forwarding for IPv6 enabled, unless the system is an IPv6 router.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# test net.ipv6.conf.all.forwarding = 0
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  (sed -En 's/^([0-9]+)$/\1/p' '/proc/sys/net/ipv6/conf/all/forwarding') | grep -qxF '0'
}
# test net.ipv6.conf.default.forwarding = 0
# textfilecontent54_object (textfilecontent54_test)
test_2() {
  (sed -En 's/^([0-9]+)$/\1/p' '/proc/sys/net/ipv6/conf/default/forwarding') | grep -qxF '0'
}
# test for all forwarding=0 in /etc/sysctl.conf
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  (sed -En 's/^[ \t\r\n]*net\.ipv6\.conf\.all\.forwarding[ \t]*=[ \t]*([0-9]+)/\1/p' '/etc/sysctl.conf') | grep -qxF '0'
}
# test for default forwarding=0 in /etc/sysctl.conf
# textfilecontent54_object (textfilecontent54_test)
test_4() {
  (sed -En 's/^[ \t\r\n]*net\.ipv6\.conf\.default\.forwarding[ \t]*=[ \t]*([0-9]+)/\1/p' '/etc/sysctl.conf') | grep -qxF '0'
}
# install ipv6 /bin/true in /etc/modprobe.conf
# textfilecontent54_object (textfilecontent54_test)
test_5() {
  grep -Pq '^[ \t\r\n]*install[ \t\r\n]+ipv6[ \t\r\n]+/bin/true' '/etc/modprobe.conf' &>/dev/null
}
# install ipv6 /bin/true in /etc/modprobe.d/*
# textfilecontent54_object (textfilecontent54_test)
test_6() {
  grep -rqP --include='*' '^[ \t\r\n]*install[ \t\r\n]+ipv6[ \t\r\n]+/bin/true' '/etc/modprobe.d' &>/dev/null
}

if ! ( ! ( test_1 && test_2 && test_3 && test_4 ) || ! ( test_5 || test_6 ) ); then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# oval:mil.disa.fso.rhel11:def:364

if [ ! -f "/proc/sys/net/ipv6/conf/all/forwarding" ] || [ ! -f "/proc/sys/net/ipv6/conf/default/forwarding" ] || \
    grep -q "^net\.ipv6\.conf\.all\.forwarding[ \t]*=[ \t]*0$" /etc/sysctl.conf && \
    grep -q "^net\.ipv6\.conf\.default\.forwarding[ \t]*=[ \t]*0$" /etc/sysctl.conf
then
    echo "PASS"
    exit 0
else
    echo "FAIL"
    exit 1
fi

Remediation

Disable IPv6 forwarding.

Edit /etc/sysctl.conf and add a setting for "net.ipv6.conf.all.forwarding=0" and "net.ipv6.conf.default.forwarding=0".

Reload the sysctls.
Procedure:
# sysctl -p