> For the complete documentation index, see [llms.txt](https://docs.nexthink.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexthink.com/security/system-hardening-classic.md).
# System Hardening (classic)
Hardening is the process of reducing the attack surface of an operating system or an application by enforcing a set of configurations in line with security best practices.
The Nexthink cloud platform relies partially on software appliances hosting [Engine (classic)](/references/references-classic/glossary-classic/engine-classic.md) and [Portal (classic)](/references/references-classic/glossary-classic/portal-classic.md). The system hardening follows the Center for Internet Security (CIS) benchmark for Oracle Linux 8 L1.
Level 1 (L1) security controls provide a clear security benefit while having a minor impact on performance and maintaining usability. All customer instances have Level 1 (L1) security control settings automatically applied.
## Hardening measures
### CIS hardening
Enforcing all the CIS L1 checks requires some degree of fine-tuning to match our product configuration. We keep those changes to a strict minimum and ensure they do not impact our product's security.
Contact [Nexthink Support](https://support.nexthink.com/) to request the list of changes.
We will keep our hardening configuration aligned with future versions of the CIS benchmark.
### CIS exceptions
Some hardening configurations are not applied as described by the CIS benchmark in the context of the Nexthink cloud platform. Those configurations are mitigated in a different way, to achieve the same objective.
Contact [Nexthink Support](https://support.nexthink.com/) to request the list of exceptions.
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