The Photon operating system must use a reverse-path filter for IPv4 network traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-256573	PHTN-30-000104	SV-256573r887393_rule		Medium

Description
Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems that are routers for complicated networks but is helpful for end hosts and routers serving small networks.

STIG	Date
VMware vSphere 7.0 vCenter Appliance Photon OS Security Technical Implementation Guide	2023-02-21

Details

Check Text ( C-60248r887391_chk )
At the command line, run the following command: # /sbin/sysctl -a --pattern "net.ipv4.conf.(all\|default\|eth.*)\.rp_filter" Expected result: net.ipv4.conf.all.rp_filter = 1 net.ipv4.conf.default.rp_filter = 1 net.ipv4.conf.eth0.rp_filter = 1 If the output does not match the expected result, this is a finding. Note: The number of "ethx" lines returned is dependent on the number of interfaces. Every "ethx" entry must be set to "1".

Check Text ( C-60248r887391_chk )

At the command line, run the following command:

# /sbin/sysctl -a --pattern "net.ipv4.conf.(all|default|eth.*)\.rp_filter"

Expected result:

net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.eth0.rp_filter = 1

If the output does not match the expected result, this is a finding.

Note: The number of "ethx" lines returned is dependent on the number of interfaces. Every "ethx" entry must be set to "1".

Fix Text (F-60191r887392_fix)
At the command line, run the following command: # for SETTING in $(/sbin/sysctl -aN --pattern "net.ipv4.conf.(all\|default\|eth.*)\.rp_filter"); do sed -i -e "/^${SETTING}/d" /etc/sysctl.conf;echo $SETTING=1>>/etc/sysctl.conf; done # /sbin/sysctl --load