Finding ID | Version | Rule ID | IA Controls | Severity |
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V-204612 | RHEL-07-040620 | SV-204612r603261_rule | Medium |
Description |
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Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router. |
STIG | Date |
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Red Hat Enterprise Linux 7 Security Technical Implementation Guide | 2020-12-08 |
Check Text ( C-4736r89028_chk ) |
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Verify the system does not accept IPv4 source-routed packets by default. # grep net.ipv4.conf.default.accept_source_route /etc/sysctl.conf /etc/sysctl.d/* net.ipv4.conf.default.accept_source_route = 0 If " net.ipv4.conf.default.accept_source_route " 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. Check that the operating system implements the accept source route variable with the following command: # /sbin/sysctl -a | grep net.ipv4.conf.default.accept_source_route net.ipv4.conf.default.accept_source_route = 0 If the returned line does not have a value of "0", this is a finding. |
Fix Text (F-4736r89029_fix) |
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Set the system to the required kernel parameter 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_source_route = 0 Issue the following command to make the changes take effect: # sysctl --system |