Finding ID | Version | Rule ID | IA Controls | Severity |
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V-257959 | RHEL-09-253020 | SV-257959r991589_rule | Medium |
Description |
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Source-routed packets allow the source of the packet to suggest 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-routerd traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router. Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It must be disabled unless it is absolutely required. |
STIG | Date |
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Red Hat Enterprise Linux 9 Security Technical Implementation Guide | 2024-06-04 |
Check Text ( C-61700r942986_chk ) |
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Verify RHEL 9 will not accept IPv4 source-routed packets. Check the value of the all "accept_source_route" variables with the following command: $ sudo sysctl net.ipv4.conf.all.accept_source_route net.ipv4.conf.all.accept_source_route = 0 If the returned line does not have a value of "0", a line is not returned, or the line is commented out, this is a finding. Check that the configuration files are present to enable this network parameter. $ sudo /usr/lib/systemd/systemd-sysctl --cat-config | egrep -v '^(#|;)' | grep -F net.ipv4.conf.all.accept_source_route | tail -1 net.ipv4.conf.all.accept_source_route = 0 If "net.ipv4.conf.all.accept_source_route" is not set to "0" or is missing, this is a finding. |
Fix Text (F-61624r925863_fix) |
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Configure RHEL 9 to ignore IPv4 source-routed packets. Add or edit the following line in a single system configuration file, in the "/etc/sysctl.d/" directory: net.ipv4.conf.all.accept_source_route = 0 Load settings from all system configuration files with the following command: $ sudo sysctl --system |