TOSS 5 must prevent Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages from being accepted.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-282703 | TOSS-05-000231 | SV-282703r1201358_rule | CCI-000366 | medium |
| Description | ||||
| ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack. | ||||
| STIG | Date | |||
| Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide | 2026-04-01 | |||
Details
Check Text (C-282703r1201358_chk)
Verify TOSS 5 will not accept IPv6 ICMP redirect messages.
Note: If IPv6 is disabled on the system, this requirement is not applicable.
Check the value of the default "accept_redirects" variables using the following command:
$ sudo sysctl net.ipv6.conf.default.accept_redirects
net.ipv6.conf.default.accept_redirects = 0
If the returned line does not have a value of "0", or a line is not returned, this is a finding.
Fix Text (F-87169r1201088_fix)
Configure TOSS 5 to prevent IPv6 ICMP redirect messages from being accepted.
Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory:
net.ipv6.conf.default.accept_redirects = 0
Load settings from all system configuration files using the following command:
$ sudo sysctl --system