TOSS must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects by default.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-253123 | TOSS-04-040820 | SV-253123r991589_rule | CCI-000366 | 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 | |||
| Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-253123r991589_chk)
Verify TOSS does not allow interfaces to perform Internet Protocol version 4 (IPv4) ICMP redirects by default.
Note: If IPv4 is disabled on the system, this requirement is Not Applicable.
Check the value of the "default send_redirects" variables with the following command:
$ sudo sysctl net.ipv4.conf.default.send_redirects
net.ipv4.conf.default.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-56526r825040_fix)
Configure TOSS to not allow interfaces to perform Internet Protocol version 4 (IPv4) ICMP redirects by default with the following command:
$ sudo sysctl -w net.ipv4.conf.default.send_redirects=0
If "0" is not the system's default value then add or update the following line in the appropriate file under "/etc/sysctl.d":
net.ipv4.conf.default.send_redirects=0