UCF STIG Viewer Logo

The system must ignore ICMPv4 redirect messages by default.


Finding ID Version Rule ID IA Controls Severity
V-217920 RHEL-06-000091 SV-217920r505923_rule Low
This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.
Red Hat Enterprise Linux 6 Security Technical Implementation Guide 2020-09-03


Check Text ( C-19401r376775_chk )
The status of the "net.ipv4.conf.default.accept_redirects" kernel parameter can be queried by running the following command:

$ sysctl net.ipv4.conf.default.accept_redirects
net.ipv4.conf.default.accept_redirects = 0

$ grep net.ipv4.conf.default.accept_redirects /etc/sysctl.conf /etc/sysctl.d/*
net.ipv4.conf.default.accept_redirects = 0

If "net.ipv4.conf.default.accept_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.
Fix Text (F-19399r376776_fix)
To set the runtime status of the "net.ipv4.conf.default.accept_redirects" kernel parameter, run the following command:

# sysctl -w net.ipv4.conf.default.accept_redirects=0

Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config 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