SV-281345r1167185: RHEL 10 must use reverse path filtering on all Internet Protocol version 4 (IPv4) interfaces. | Red Hat Enterprise Linux 10 STIG SCAP Benchmark

Loading benchmark…

Assessment Title

Rule Text

RHEL 10 must use reverse path filtering on all Internet Protocol version 4 (IPv4) interfaces.

Description

Discussion Text

Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface on which they were received. It must not be used on systems that are routers for complicated networks but is helpful for end hosts and routers serving small networks. Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00076

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

IA Controls

NIST SP 800-53

Not mappedCCI-002385Not mappedCCI-001100

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:281345
# RHEL 10 must use reverse path filtering on all Internet Protocol version 4 (IPv4) interfaces.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# net.ipv4.conf.all.rp_filter setting in kernel is 1
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/net/ipv4/conf/all/rp_filter)" -eq 1 ]
}

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
# oval:mil.disa.stig.rhel10os:def:281345
if ! command -v sysctl >/dev/null; then
    echo "FAIL"
    exit 1
fi
if [ ! -f /etc/sysctl.d/99-ipv4_rp_filter.conf ]; then
    echo "FAIL"
    exit 1
fi
if grep -q "^net.ipv4.conf.all.rp_filter = 1$" /etc/sysctl.d/99-ipv4_rp_filter.conf; then
    echo "PASS"
    exit 0
else
    echo "FAIL"
    exit 1
fi

Remediation

Configure RHEL 10 to use reverse path filtering on all IPv4 interfaces.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/99-ipv4_rp_filter.conf

Add the following line to the file:

net.ipv4.conf.all.rp_filter = 1

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

$ sudo sysctl --system