# Cis Ubuntu1804 V220 3 4 2 1

> Ensure nftables is installed

- Skill: `cyberstrikeus/cis-ubuntu1804-v220-3-4-2-1` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1804-v220-3-4-2-1`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1804-v220-3-4-2-1/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-ubuntu1804-v220-3-4-2-1

---


# CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 3.4.2.1

## 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 queueing component and logging subsystem.

## 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.

## Impact

None.

## 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
```

## Default Value

nftables is not installed by default.

## References

1. NIST SP 800-53 Rev. 5: CA-9, SC-7
2. CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0

## CIS Controls

Version 8

4.4 Implement and Manage a Firewall on Servers - Implement and manage a firewall on servers, where supported.

4.5 Implement and Manage a Firewall on End-User Devices - Implement and manage a host-based firewall or port-filtering tool on end-user devices.

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.

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Assessment Status

Automated