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3.2.6 Ensure bogus ICMP responses are ignored (Scored)
Profile Applicability
Level 1 - Server Level 1 - Workstation
Description
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.
Audit
Run the following command and verify output matches:
# sysctl net.ipv4.icmp_ignore_bogus_error_responses net.ipv4.icmp_ignore_bogus_error_responses = 1
Remediation
Set the following parameter in the “/etc/sysctl.conf” 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