# Cis Ubuntu1604 V200 3 5 2 1

> Ensure nftables is installed

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-3-5-2-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-3-5-2-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-3-5-2-1/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-ubuntu1604-v200-3-5-2-1

---


# CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 3.5.2.1

## Profile

- **Level:** Level 1 - Server, Level 1 - Workstation
- **Assessment Status:** Automated

## Description

nftables provides a new in-kernel packet classification framework that is based on a network-specific Virtual Machine (VM) and a new nft userspace command line tool. nftables reuses the existing Netfilter subsystems such as the existing hook infrastructure, the connection tracking system, NAT, userspace queuing and logging subsystem.

Notes:

- nftables is available in Linux kernel 3.13 and newer.
- Only one firewall utility should be installed and configured.
- Changing firewall settings while connected over the network can result in being locked out of the system.

## Rationale

nftables is a subsystem of the Linux kernel that can protect against threats originating from within a corporate network to include malicious mobile code and poorly configured software on a host.

## Audit Procedure

### Command Line

Run the following command to verify that nftables is installed:

```bash
dpkg-query -s nftables | grep 'Status: install ok installed'
```

## Expected Result

```
Status: install ok installed
```

## Remediation

### Command Line

Run the following command to install nftables:

```bash
apt install nftables
```

## References

None

## CIS Controls

Version 7

9.4 Apply Host-based Firewalls or Port Filtering - Apply host-based firewalls or port filtering tools on end systems, with a default-deny rule that drops all traffic except those services and ports that are explicitly allowed.