Title

The SUSE operating system must not forward Internet Protocol version 4 (IPv4) source-routed packets by default. (Cat II impact)

Discussion

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.

Check Content

Verify the SUSE operating system does not accept IPv4 source-routed packets by default. Check the value of the default IPv4 accept source route variable with the following command: > sudo sysctl net.ipv4.conf.default.accept_source_route net.ipv4.conf.default.accept_source_route = 0 If the network parameter "ipv4.conf.default.accept_source_route" is not equal to "0" or nothing is returned, this is a finding.

Fix Text

Configure the SUSE operating system to disable IPv4 default source routing by running the following command as an administrator: > sudo sysctl -w net.ipv4.conf.default.accept_source_route=0 If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf": > sudo sh -c 'echo "net.ipv4.conf.default.accept_source_route=0" >> /etc/sysctl.d/99-stig.conf' > sudo sysctl --system

Additional Identifiers

Rule ID: SV-235016r622137_rule

Vulnerability ID: V-235016

Group Title: SRG-OS-000480-GPOS-00227

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