3.2.6 Ensure bogus ICMP responses are ignored - 'net.ipv4.icmp_ignore_bogus_error_responses = 1'

Information

Setting 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.

Rationale:

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 /etc/sysctl.d/* file:

net.ipv4.icmp_ignore_bogus_error_responses = 1

Run the following commands to set the active kernel parameters:

# sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1
# sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/files/2420