How do I install the Cis GCP Cos 3.3.1.3 skill?

Run npx skillmds@latest add cyberstrikeus/cis-gcp-cos-3-3-1-3 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Cis GCP Cos 3.3.1.3 skill do?

Ensure IPv6 outbound and established connections are configured It is listed under DevOps & Infra on SkillMD.

Is Cis GCP Cos 3.3.1.3 safe to use?

SkillMD's automated safety review verdict for this skill is PASS. Independent scanners report: SkillSpector: CAUTION, Skill Scanner: PASS. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Cis GCP Cos 3.3.1.3?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Cis GCP Cos 3.3.1.3 free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Cis GCP Cos 3.3.1.3?

cyberstrikeus (@cyberstrikeus) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Cis GCP Cos 3.3.1.3 by cyberstrikeus

Name: Cis GCP Cos 3.3.1.3
Author: cyberstrikeus

File contents

3.3.1.3 Ensure IPv6 outbound and established connections are configured (Manual)

Description

Configure the firewall rules for new outbound, and established IPv6 connections.

Rationale

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

Impact

Changing firewall settings while connected over network can result in being locked out of the system.

Remediation will only affect the active system firewall, be sure to configure the default policy in your firewall management to apply on boot as well.

Audit Procedure

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

ip6tables -L -v -n

Expected Result

Verify that outbound and established connections are configured in accordance with site policy. The output should show rules allowing NEW and ESTABLISHED outbound connections and ESTABLISHED inbound connections for tcp, udp, and icmp protocols.

Remediation

Configure iptables in accordance with site policy. The following commands will implement a policy to allow all outbound connections and all established connections:

ip6tables -A OUTPUT -p tcp -m state --state NEW,ESTABLISHED -j ACCEPT
ip6tables -A OUTPUT -p udp -m state --state NEW,ESTABLISHED -j ACCEPT
ip6tables -A OUTPUT -p icmp -m state --state NEW,ESTABLISHED -j ACCEPT
ip6tables -A INPUT -p tcp -m state --state ESTABLISHED -j ACCEPT
ip6tables -A INPUT -p udp -m state --state ESTABLISHED -j ACCEPT
ip6tables -A INPUT -p icmp -m state --state ESTABLISHED -j ACCEPT

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	4.4 Implement and Manage a Firewall on Servers - Implement and manage a firewall on servers, where supported. Example implementations include a virtual firewall, operating system firewall, or a third-party firewall agent.	x	x	x
v7	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.	x	x	x

Profile

Level 2 - Server

---name: cis-gcp-cos-3-3-1-3description: Ensure IPv6 outbound and established connections are configured---# 3.3.1.3 Ensure IPv6 outbound and established connections are configured (Manual)## DescriptionConfigure the firewall rules for new outbound, and established IPv6 connections.## RationaleIf rules are not in place for new outbound, and established connections all packets will be dropped by the default policy preventing network usage.## ImpactChanging firewall settings while connected over network can result in being locked out of the system.Remediation will only affect the active system firewall, be sure to configure the default policy in your firewall management to apply on boot as well.## Audit ProcedureRun the following command and verify all rules for new outbound, and established connections match site policy:```baship6tables -L -v -n```## Expected ResultVerify that outbound and established connections are configured in accordance with site policy. The output should show rules allowing NEW and ESTABLISHED outbound connections and ESTABLISHED inbound connections for tcp, udp, and icmp protocols.## RemediationConfigure iptables in accordance with site policy. The following commands will implement a policy to allow all outbound connections and all established connections:```baship6tables -A OUTPUT -p tcp -m state --state NEW,ESTABLISHED -j ACCEPTip6tables -A OUTPUT -p udp -m state --state NEW,ESTABLISHED -j ACCEPTip6tables -A OUTPUT -p icmp -m state --state NEW,ESTABLISHED -j ACCEPTip6tables -A INPUT -p tcp -m state --state ESTABLISHED -j ACCEPTip6tables -A INPUT -p udp -m state --state ESTABLISHED -j ACCEPTip6tables -A INPUT -p icmp -m state --state ESTABLISHED -j ACCEPT```## CIS Controls| Controls Version | Control | IG 1 | IG 2 | IG 3 || ---------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- || v8 | **4.4 Implement and Manage a Firewall on Servers** - Implement and manage a firewall on servers, where supported. Example implementations include a virtual firewall, operating system firewall, or a third-party firewall agent. | x | x | x || v7 | **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. | x | x | x |## Profile- Level 2 - Server

Frequently asked questions

Cis GCP Cos 3.3.1.3