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RHEL 8 must not be performing packet forwarding unless the system is a router.


Overview

Finding ID Version Rule ID IA Controls Severity
V-230540 RHEL-08-040260 SV-230540r627750_rule Medium
Description
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this software is used when not required, system network information may be unnecessarily transmitted across the network.
STIG Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide 2021-03-04

Details

Check Text ( C-33209r568366_chk )
Verify RHEL 8 is not performing packet forwarding, unless the system is a router.

Note: If either IPv4 or IPv6 is disabled on the system, this requirement only applies to the active internet protocol version.

Check to see if IP forwarding is enabled using the following commands:

$ sudo sysctl net.ipv4.ip_forward

net.ipv4.ip_forward = 0

$ sudo sysctl net.ipv6.conf.all.forwarding

net.ipv6.conf.all.forwarding = 0

If IP forwarding value is not "0" and is not documented with the Information System Security Officer (ISSO) as an operational requirement, this is a finding.
Fix Text (F-33184r568367_fix)
Configure RHEL 8 to not allow packet forwarding, unless the system is a router with the following commands:

$ sudo sysctl -w net.ipv4.ip_forward=0

$ sudo sysctl -w net.ipv6.conf.all.forwarding=0

If "0" is not the system's default value then add or update the following lines in the appropriate file under "/etc/sysctl.d":

net.ipv4.ip_forward=0

net.ipv6.conf.all.forwarding=0