3.3.4 Ensure suspicious packets are logged - 'net.ipv4.conf.default.log_martians = 1 /sbin/sysctl'

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

See Also

https://workbench.cisecurity.org/files/3144

Item Details

Category: AUDIT AND ACCOUNTABILITY

References: 800-53|AU-3, 800-53|AU-12, CSCv6|6, CSCv7|6.2, CSCv7|6.3

Plugin: Unix

Control ID: 11896f783a367c90f3fa05099aed1865ccaaf0f5337f543c1e61cc7f7b609af9