Lynis Security Controls
KRNL-6000 - Kernel sysctl values
By means of sysctl values we can adjust kernel related parameters. Many of them are related to hardening of the network stack, how the kernel deals with processes or files. This control is a generic test with several sysctl variables (configured by the scan profile).
How to solve
The Linux kernel can be tuned with the sysctl command. It uses a list of kernel parameters, which alter how the kernel should behave within the areas of storage, network, memory management, and more.
Lynis has a default list of best practice values for sysctl. They are tested within this particular control, with a related suggestion when the actual value on the system is different than the expected value. This does not always mean the system is weakly configured. It depends on the primary goal of the system, and its focus area(s). A system with the role to be a router will have to be tuned more aggressively when it comes to the network stack. Production systems with a lot of write activity to the hard disks might need tuning when it comes to buffering.
We suggest to check each discovered key and determine the best value for your system. There is not a "one size fits all" solution here. The additional resources might be useful for further analysis. Also in our Enterprise version we have more details available to help you tuning your systems.
- Linux sysctl keys and descriptions (Describes the available keys and what they do, or how they impact the system)
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Linux and Unix System Hardening
This information is provided as part of the Lynis community project. It is related to Lynis control KRNL-6000. All information should be considered as-is, without guarantees. Any advice or snippets should be tested before implementing in production environments.
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