RHEL-07-040640 - The Red Hat Enterprise Linux operating system must prevent Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages from being accepted.

Information

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.

Solution

Set the system to not accept IPv4 ICMP redirect messages 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.accept_redirects = 0

Issue the following command to make the changes take effect:

# sysctl --system

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_RHEL_7_V3R15_STIG.zip

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-204614r991589_rule, STIG-ID|RHEL-07-040640, STIG-Legacy|SV-86913, STIG-Legacy|V-72289, Vuln-ID|V-204614

Plugin: Unix

Control ID: 7e243f31fdc6b028673b253c27ad3a1ec5f957584346d5c0ad9e43820e96504f