Changes are coming to https://stigviewer.com.
Take our survey to help us understand your usage and how we can better serve you in the future.
Take Survey
RHEL 9 must ignore Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-257958 | RHEL-09-253015 | SV-257958r991589_rule | 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 |
|---|---|
| Red Hat Enterprise Linux 9 Security Technical Implementation Guide | 2024-06-04 |
Details
| Check Text ( C-61699r942984_chk ) |
|---|
| Verify RHEL 9 will not accept IPv4 ICMP redirect messages. Check the value of the all "accept_redirects" variables with 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", a line is not returned, or the line is commented out, this is a finding. Check that the configuration files are present to enable this network parameter. $ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F net.ipv4.conf.all.accept_redirects | tail -1 net.ipv4.conf.all.accept_redirects = 0 If "net.ipv4.conf.all.accept_redirects" is not set to "0" or is missing, this is a finding. |
| Fix Text (F-61623r925860_fix) |
|---|
| Configure RHEL 9 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 with the following command: $ sudo sysctl --system |