# Cis Ubuntu2004 V300 4 2 6

> Ensure ufw outbound connections are configured

- Skill: `cyberstrikeus/cis-ubuntu2004-v300-4-2-6` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu2004-v300-4-2-6`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu2004-v300-4-2-6/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector CAUTION)
- 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-ubuntu2004-v300-4-2-6

---


# CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0 - Control 4.2.6

## Profile

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

## Description

Configure the firewall rules for new outbound connections.

Note:

- Changing firewall settings while connected over network can result in being locked out of the system
- Unlike iptables, when a new outbound rule is added, ufw automatically takes care of associated established connections, so no rules for the latter kind are required.

## Rationale

If rules are not in place for new outbound connections all packets will be dropped by the default policy preventing network usage.

## Audit Procedure

### Command Line

Run the following command and verify all rules for new outbound connections match site policy:

```bash
ufw status numbered
```

## Expected Result

Output should show rules that match site policy for outbound connections.

## Remediation

### Command Line

Configure ufw in accordance with site policy. The following commands will implement a policy to allow all outbound connections on all interfaces:

```bash
ufw allow out on all
```

## Default Value

Not applicable.

## References

1. NIST SP 800-53 Rev. 5: SC-7

## CIS Controls

v8 - 4.4 Implement and Manage a Firewall on Servers
v8 - 4.5 Implement and Manage a Firewall on End-User Devices
v7 - 9.4 Apply Host-based Firewalls or Port Filtering

MITRE ATT&CK Mappings: T1562, T1562.004 | TA0011 | M1031, M1037