The system must not accept IPv4 source-routed packets on any interface.

From Red Hat Enterprise Linux 6 Security Technical Implementation Guide

Associated with: CCI-000366

SV-50324r2_rule The system must not accept IPv4 source-routed packets on any interface.

Vulnerability discussion

Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.

Check content

The status of the "net.ipv4.conf.all.accept_source_route" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.all.accept_source_route 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_source_route /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_source_route" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.all.accept_source_route=0 If this is not the system's default value, add the following line to "/etc/sysctl.conf": net.ipv4.conf.all.accept_source_route = 0

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