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V-256573

CAT II (Medium)

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

Rule ID

SV-256573r991589_rule

STIG

VMware vSphere 7.0 vCenter Appliance Photon OS Security Technical Implementation Guide

Version

V1R4

CCIs

CCI-000366

Discussion

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.

Check Content

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

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