SLEM 5 must not forward Internet Protocol version 4 (IPv4) source-routed packets.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-261313 | SRG-OS-000480-GPOS-00227 | SLEM-05-253010 | SV-261313r996409_rule | 2024-06-04 | 1 |
| 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/IPv6 forwarding is enabled and the system is functioning as a router. |
| ℹ️ Check |
|---|
| Verify SLEM 5 does not accept IPv4 source-routed packets with the following command: > sudo sysctl net.ipv4.conf.all.accept_source_route net.ipv4.conf.all.accept_source_route = 0 If the network parameter "ipv4.conf.all.accept_source_route" is not equal to "0", or nothing is returned, this is a finding. |
| ✔️ Fix |
|---|
| Configure SLEM 5 to disable IPv4 source routing by running the following command as an administrator: > sudo sysctl -w net.ipv4.conf.all.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.all.accept_source_route=0" >> /etc/sysctl.d/99-stig.conf' > sudo sysctl --system |