======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