The system must not accept ICMPv4 redirect packets on any interface.

From Red Hat Enterprise Linux 6 Security Technical Implementation Guide

Associated with: CCI-000366

SV-50325r2_rule The system must not accept ICMPv4 redirect packets on any interface.

Vulnerability discussion

Accepting ICMP redirects has few legitimate uses. It should be disabled unless it is absolutely required.

Check content

The status of the "net.ipv4.conf.all.accept_redirects" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.all.accept_redirects The output of the command should indicate a value of "0". If this value is not the default value, investigate how it could have been adjusted at runtime, and verify it is not set improperly in "/etc/sysctl.conf". $ grep net.ipv4.conf.all.accept_redirects /etc/sysctl.conf If the correct value is not returned, this is a finding.

Fix text

To set the runtime status of the "net.ipv4.conf.all.accept_redirects" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.all.accept_redirects=0 If this is not the system's default value, add the following line to "/etc/sysctl.conf": net.ipv4.conf.all.accept_redirects = 0

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