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RHEL-10-800190 RHEL 10 must not send Internet Control Message Protocol (ICMP) redirects.

DISA STIG library V1R3
All changes in this version
first version loaded CAT II

Maps to SC-5, SC-7(4) via CCI-002385, CCI-001106

Title

RHEL 10 must not send Internet Control Message Protocol (ICMP) redirects.

Control

Verify RHEL 10 does not send IPv4 ICMP redirect messages. Check the value of the "net.ipv4.conf.all.send_redirects" variables with the following command: $ sudo sysctl net.ipv4.conf.all.send_redirects net.ipv4.conf.all.send_redirects = 0 If "net.ipv4.conf.all.send_redirects" is not set to "0" and is not documented with the information system security officer as an operational requirement or is missing, this is a finding.

Discussion

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. The ability to send ICMP redirects is only appropriate for systems acting as routers. Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00082

Related controls

CCI-001106, CCI-002385

Fix

Configure RHEL 10 to not send IPv4 ICMP redirect messages. Create a configuration file if it does not already exist: $ sudo vi /etc/sysctl.d/ipv4_send_redirects.conf Add the following line to the file: net.ipv4.conf.all.send_redirects = 0 Reload settings from all system configuration files with the following command: $ sudo sysctl --system