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OL 8 must not send Internet Control Message Protocol (ICMP) redirects.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
|---|---|---|---|---|
| V-248877 | OL08-00-040220 | SV-248877r780197_rule | Medium |
| Description |
|---|
| ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table, possibly revealing portions of the network topology. There are notable differences between Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). There is only a directive to disable sending of IPv4 redirected packets. Refer to RFC4294 for an explanation of "IPv6 Node Requirements", which resulted in this difference between IPv4 and IPv6. |
| STIG | Date |
|---|---|
| Oracle Linux 8 Security Technical Implementation Guide | 2021-07-21 |
Details
| Check Text ( C-52311r780195_chk ) |
|---|
| Verify OL 8 does not send IPv4 ICMP redirect messages. Note: If IPv4 is disabled on the system, this requirement is not applicable. Check the value of the "all send_redirects" variables with the following command: $ sudo sysctl net.ipv4.conf.all.send_redirects net.ipv4.conf.all.send_redirects = 0 If the returned line does not have a value of "0" or a line is not returned, this is a finding. |
| Fix Text (F-52265r780196_fix) |
|---|
| Configure OL 8 to not allow interfaces to perform IPv4 ICMP redirects with the following command: $ sudo sysctl -w net.ipv4.conf.all.send_redirects=0 If "0" is not the system's default value, add or update the following line in "/etc/sysctl.conf" or in the appropriate file under "/etc/sysctl.d": net.ipv4.conf.all.send_redirects=0 |