SV-281354r1167212: RHEL 10 must not accept router advertisements on all Internet Protocol version 6 (IPv6) interfaces. | Red Hat Enterprise Linux 10 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 10 must not accept router advertisements on all Internet Protocol version 6 (IPv6) interfaces.

Description

Discussion Text

An illicit router advertisement message could result in a man-in-the-middle attack. Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00085

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

IA Controls

NIST SP 800-53

Not mappedCCI-002385Not mappedCCI-001109

References

DPMS Target Red Hat Enterprise Linux 10 DISA DPMS Target Red Hat Enterprise Linux 10 5733

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.stig.rhel10os:def:281354
# RHEL 10 must not accept router advertisements on all Internet Protocol version 6 (IPv6) interfaces.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# net.ipv6.conf.all.accept_ra setting in kernel is set to 0
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/net/ipv6/conf/all/accept_ra)" -eq 0 ]
}

if test_1; 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
# DISA STIG RHEL 10 must not accept router advertisements on all Internet Protocol version 6 (IPv6) interfaces - oval:mil.disa.stig.rhel10os:def:281354

if ! command -v sysctl >/dev/null; then
    echo "FAIL"
    exit 1
fi

if ! [ -f /etc/sysctl.d/ipv4_accept_ra.conf ]; then
    echo "PASS"
    exit 0
fi

if grep -qF 'net.ipv6.conf.all.accept_ra = 0' /etc/sysctl.d/ipv4_accept_ra.conf; then
    echo "PASS"
    exit 0
fi

echo "FAIL"
exit 1

Remediation

Configure RHEL 10 to not accept router advertisements on all IPv6 interfaces, unless the system is a router.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/ipv4_accept_ra.conf

Add the following line to the file:

net.ipv6.conf.all.accept_ra = 0

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system