Ensure bogus ICMP responses are ignored - sysctl

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. 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://www.cisco.com/c/en/us/td/docs/security/firepower/623/configuration/guide/fpmc-config-guide-v623.html

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7(12), CSCv6|3, CSCv6|11

Plugin: Unix

Control ID: eaa9ebbeb91b8b97e7ab5e560cc02004c47016ae3f72f32a57acc31f1a9f66d9