OL 9 must not forward IPv6 source-routed packets.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-271879 | SRG-OS-000480-GPOS-00227 | OL09-00-006042 | SV-271879r1092349_rule | 2026-02-17 | 1 |
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 forwarding is enabled and the system is functioning as a router.
ℹ️ Check
Note: If IPv6 is disabled on the system, this requirement is Not Applicable.
Verify that OL 9 does not accept IPv6 source-routed packets.
Check the value of the accept source route variable with the following command:
$ sysctl net.ipv6.conf.all.accept_source_route
net.ipv6.conf.all.accept_source_route = 0
If the returned line does not have a value of "0", a line is not returned, or the line is commented out, this is a finding.
✔️ Fix
Configure OL 9 to not forward IPv6 source-routed packets.
Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory:
net.ipv6.conf.all.accept_source_route = 0
Load settings from all system configuration files with the following command:
$ sudo sysctl --system