SLEM 5 must not forward Internet Protocol version 4 (IPv4) source-routed packets by default.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-261314 | SLEM-05-253015 | SV-261314r996412_rule | CCI-000366 | medium |
| Description | ||||
| 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 | |||
| SUSE Linux Enterprise Micro (SLEM) 5 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-261314r996412_chk)
Verify SLEM 5 does not accept IPv4 source-routed packets by default 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 (F-64951r996411_fix)
Configure SLEM 5 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