3.2.6 Ensure bogus ICMP responses are ignored (Scored)

Level 1 - Server
Level 1 - Workstation 

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.

Run the following command and verify output matches:

# sysctl net.ipv4.icmp_ignore_bogus_error_responses 
net.ipv4.icmp_ignore_bogus_error_responses = 1

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