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cis-ubuntu1204-v110-7-3-2

DevOps & Security
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Disable IPv6 Redirect Acceptance

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How to use this skill

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Prompt to paste
I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_12.04_LTS_Server_Benchmark_v1.1.0/cis-ubuntu1204-v110-7-3-2/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/cis-ubuntu1204-v110-7-3-2/. Do not write files or run scripts until I approve.

After I approve, install the complete skill folder, including required referenced files, into that project location. Verify it is discoverable, then tell me its actual invocation name and how to use it. Do not claim it is installed until you have verified it.

Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

7.3.2 Disable IPv6 Redirect Acceptance (Not Scored)

Profile Applicability

  • Level 1

Description

This setting prevents the system from accepting ICMP redirects. ICMP redirects tell the system about alternate routes for sending traffic.

Rationale

It is recommended that systems not accept ICMP redirects as they could be tricked into routing traffic to compromised machines. Setting hard routes within the system (usually a single default route to a trusted router) protects the system from bad routes.

Audit Procedure

Using Command Line

Perform the following to determine if IPv6 redirects are disabled.

/sbin/sysctl net.ipv6.conf.all.accept_redirects
/sbin/sysctl net.ipv6.conf.default.accept_redirects

Expected Result

net.ipv6.conf.all.accept_redirect = 0
net.ipv6.conf.default.accept_redirect = 0

Remediation

Using Command Line

Set the net.ipv6.conf.all.accept_redirects and net.ipv6.conf.default.accept_redirects parameters to 0 in /etc/sysctl.conf:

net.ipv6.conf.all.accept_redirects=0
net.ipv6.conf.default.accept_redirects=0

Modify active kernel parameters to match:

/sbin/sysctl -w net.ipv6.conf.all.accept_redirects=0
/sbin/sysctl -w net.ipv6.conf.default.accept_redirects=0
/sbin/sysctl -w net.ipv6.route.flush=1

Default Value

IPv6 redirect acceptance is enabled by default.

References

  • CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Not Scored