# CIS Ubuntu 14.04 LTS - 3.1.2 Ensure packet redirect sending is disabled

> Verify that ICMP packet redirect sending is disabled to prevent routing information disclosure

- Skill: `cyberstrikeus/cis-ubuntu-14-04-lts-3-1-2-ensure-packet-redirect-sending-is` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu-14-04-lts-3-1-2-ensure-packet-redirect-sending-is`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu-14-04-lts-3-1-2-ensure-packet-redirect-sending-is/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-ubuntu-14-04-lts-3-1-2-ensure-packet-redirect-sending-is

---


# 3.1.2 Ensure packet redirect sending is disabled (Scored)

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

ICMP Redirects are used to send routing information to other hosts. As a host itself does not act as a router (in a host only configuration), there is no need to send redirects.

## Rationale

An attacker could use a compromised host to send invalid ICMP redirects to other router devices in an attempt to corrupt routing and have users access a system set up by the attacker as opposed to a valid system.

## Audit Procedure

Run the following commands and verify output matches:

```bash
sysctl net.ipv4.conf.all.send_redirects
# Expected: net.ipv4.conf.all.send_redirects = 0

sysctl net.ipv4.conf.default.send_redirects
# Expected: net.ipv4.conf.default.send_redirects = 0

grep "net\.ipv4\.conf\.all\.send_redirects" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv4.conf.all.send_redirects = 0

grep "net\.ipv4\.conf\.default\.send_redirects" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv4.conf.default.send_redirects= 0
```

## Expected Result

```
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
```

## Remediation

Set the following parameters in `/etc/sysctl.conf` or a `/etc/sysctl.d/*` file:

```
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
```

Run the following commands to set the active kernel parameters:

```bash
sysctl -w net.ipv4.conf.all.send_redirects=0
sysctl -w net.ipv4.conf.default.send_redirects=0
sysctl -w net.ipv4.route.flush=1
```

## Default Value

Not specified. Note: It has been reported that due to Ubuntu bug #50093 this setting (and some others) can fail to apply properly on reboot requiring it to be manually re-applied. One method of accomplishing this is to add `sysctl -p` to run on reboot to your systems crontab.

## References

- CIS Controls: 3 - Secure Configurations for Hardware and Software on Mobile Devices, Laptops, Workstations, and Servers
- CIS Controls: 11 - Secure Configurations for Network Devices such as Firewalls, Routers and switches

## Profile

- Level 1 - Server
- Level 1 - Workstation