TOSS 5 must ignore Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-282685 | TOSS-05-000213 | SV-282685r1201035_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. This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required. | ||||
| STIG | Date | |||
| Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide | 2026-04-01 | |||
Details
Check Text (C-282685r1201035_chk)
Verify TOSS 5 will not accept IPv4 ICMP redirect messages using the following command:
$ sudo sysctl net.ipv4.conf.all.accept_redirects
net.ipv4.conf.all.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-87151r1201034_fix)
Configure TOSS 5 to ignore IPv4 ICMP redirect messages.
Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory:
net.ipv4.conf.all.accept_redirects = 0
Load settings from all system configuration files using the following command:
$ sudo sysctl --system