3.3.3 Ensure bogus icmp responses are ignored

Information

Setting net.ipv4.icmp_ignore_bogus_error_responses to 1 prevents the kernel from logging bogus responses (RFC-1122 non-compliant) from broadcast reframes, keeping file systems from filling up with useless log messages.

Some routers (and some attackers) will send responses that violate RFC-1122 and attempt to fill up a log file system with many useless error messages.

Solution

Set the following parameter in /etc/sysctl.conf or a file in /etc/sysctl.d/ ending inconf :

- net.ipv4.icmp_ignore_bogus_error_responses = 1

Example:

# printf '%s
' "net.ipv4.icmp_ignore_bogus_error_responses = 1" >> /etc/sysctl.d/60-netipv4_sysctl.conf

Run the following script to set the active kernel parameters:

#!/usr/bin/env bash

{
sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1
sysctl -w net.ipv4.route.flush=1
}

Note: If these settings appear in a canonically later file, or later in the same file, these settings will be overwritten

See Also

https://workbench.cisecurity.org/benchmarks/18208

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2

Plugin: Unix

Control ID: 3e0fdd130b03f82ab67cd404b43c68ae2e701d889d9a6bfceb1d6f2e55aadd95