Information
When enabled, this feature logs packets with un-routable source addresses to the kernel log.
Rationale:
Enabling this feature and logging these packets allows an administrator to investigate the possibility that an attacker is sending spoofed packets to their system.
Solution
Set the following parameters in /etc/sysctl.conf or a /etc/sysctl.d/* file:
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
Run the following commands to set the active kernel parameters:
# sysctl -w net.ipv4.conf.all.log_martians=1
# sysctl -w net.ipv4.conf.default.log_martians=1
# sysctl -w net.ipv4.route.flush=1