TOSS 5 must not accept router advertisements on all Internet Protocol version 6 (IPv6) interfaces by default.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-282702 | SRG-OS-000480-GPOS-00227 | TOSS-05-000230 | SV-282702r1201356_rule | 2026-04-01 | 1 |
Description
An illicit router advertisement message could result in a man-in-the-middle attack.
ℹ️ Check
Verify TOSS 5 does not accept router advertisements on all IPv6 interfaces by default, unless the system is a router.
Note: If IPv6 is disabled on the system, this requirement is not applicable.
Determine if router advertisements are not accepted by default by using the following command:
$ sudo sysctl net.ipv6.conf.default.accept_ra
net.ipv6.conf.default.accept_ra = 0
If the "accept_ra" value is not "0" and is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.
✔️ Fix
Configure TOSS 5 to not accept router advertisements on all IPv6 interfaces by default unless the system is a router.
Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory:
net.ipv6.conf.default.accept_ra = 0
Load settings from all system configuration files using the following command:
$ sudo sysctl --system