The Red Hat Enterprise Linux operating system must not allow interfaces to perform Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects by default.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-204616 | RHEL-07-040650 | SV-204616r603261_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 contain information from the system's route table, possibly revealing portions of the network topology. |
| STIG | Date |
|---|---|
| Red Hat Enterprise Linux 7 Security Technical Implementation Guide | 2021-03-01 |
Details
| Check Text ( C-4740r89040_chk ) |
|---|
| Verify the system does not allow interfaces to perform IPv4 ICMP redirects by default. # grep 'net.ipv4.conf.default.send_redirects' /etc/sysctl.conf /etc/sysctl.d/* If "net.ipv4.conf.default.send_redirects" is not configured in the "/etc/sysctl.conf" file or in the /etc/sysctl.d/ directory, is commented out or does not have a value of "0", this is a finding. Check that the operating system implements the "default send_redirects" variables with the following command: # /sbin/sysctl -a | grep 'net.ipv4.conf.default.send_redirects' net.ipv4.conf.default.send_redirects = 0 If the returned line does not have a value of "0", this is a finding. |
| Fix Text (F-4740r89041_fix) |
|---|
| Configure the system to not allow interfaces to perform IPv4 ICMP redirects by default. Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value): net.ipv4.conf.default.send_redirects = 0 Issue the following command to make the changes take effect: # sysctl --system |