# Cis Ubuntu1204 V110 7 3 2

> Disable IPv6 Redirect Acceptance

- Skill: `cyberstrikeus/cis-ubuntu1204-v110-7-3-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1204-v110-7-3-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1204-v110-7-3-2/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-ubuntu1204-v110-7-3-2

---


# 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.

```bash
/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`:

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

Modify active kernel parameters to match:

```bash
/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