cyberstrikeus CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 3.3.4
Description
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.
Impact
None.
Audit Procedure
Command Line
Run the following commands and verify output matches:
sysctl net.ipv4.conf.all.log_martians
sysctl net.ipv4.conf.default.log_martians
grep "net\.ipv4\.conf\.all\.log_martians" /etc/sysctl.conf /etc/sysctl.d/*
grep "net\.ipv4\.conf\.default\.log_martians" /etc/sysctl.conf /etc/sysctl.d/*
Expected Result
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
And the grep commands should return:
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
Remediation
Command Line
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
Default Value
log_martians is disabled (set to 0) by default.
References
- CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
CIS Controls
Version 7
6.2 Activate audit logging - Ensure that local logging has been enabled on all systems and networking devices.
6.3 Enable Detailed Logging - Enable system logging to include detailed information such as an event source, date, user, timestamp, source addresses, destination addresses, and other useful elements.
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Assessment Status
Automated