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The Oracle Linux operating system must not forward Internet Protocol version 4 (IPv4) source-routed packets.


Overview

Finding ID Version Rule ID IA Controls Severity
V-221873 OL07-00-040610 SV-221873r880636_rule Medium
Description
Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router.
STIG Date
Oracle Linux 7 Security Technical Implementation Guide 2023-03-06

Details

Check Text ( C-23588r880634_chk )
Verify the system does not accept IPv4 source-routed packets.

# grep -r net.ipv4.conf.all.accept_source_route /run/sysctl.d/* /etc/sysctl.d/* /usr/local/lib/sysctl.d/* /usr/lib/sysctl.d/* /lib/sysctl.d/* /etc/sysctl.conf 2> /dev/null
net.ipv4.conf.all.accept_source_route = 0

If "net.ipv4.conf.all.accept_source_route" is not configured in the /etc/sysctl.conf file or in any of the other sysctl.d directories, is commented out, or does not have a value of "0", this is a finding.

Check that the operating system implements the accept source route variable with the following command:

# /sbin/sysctl -a | grep net.ipv4.conf.all.accept_source_route
net.ipv4.conf.all.accept_source_route = 0

If the returned line does not have a value of "0", this is a finding.

If conflicting results are returned, this is a finding.
Fix Text (F-23577r880635_fix)
Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value):

net.ipv4.conf.all.accept_source_route = 0

Issue the following command to make the changes take effect:

# sysctl -system