# CIS Ubuntu 14.04 LTS - 3.2.6 Ensure bogus ICMP responses are ignored

> Verify that bogus ICMP error responses are ignored to prevent log file pollution

- Skill: `cyberstrikeus/cis-ubuntu-14-04-lts-3-2-6-ensure-bogus-icmp-responses-are-i` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu-14-04-lts-3-2-6-ensure-bogus-icmp-responses-are-i`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu-14-04-lts-3-2-6-ensure-bogus-icmp-responses-are-i/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-3-2-6-ensure-bogus-icmp-responses-are-i

---


# 3.2.6 Ensure bogus ICMP responses are ignored (Scored)

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

Setting `icmp_ignore_bogus_error_responses` to 1 prevents the kernel from logging bogus responses (RFC-1122 non-compliant) from broadcast reframes, keeping file systems from filling up with useless log messages.

## Rationale

Some routers (and some attackers) will send responses that violate RFC-1122 and attempt to fill up a log file system with many useless error messages.

## Audit Procedure

Run the following commands and verify output matches:

```bash
sysctl net.ipv4.icmp_ignore_bogus_error_responses
# Expected: net.ipv4.icmp_ignore_bogus_error_responses = 1

grep "net\.ipv4\.icmp_ignore_bogus_error_responses" /etc/sysctl.conf /etc/sysctl.d/*
# Expected: net.ipv4.icmp_ignore_bogus_error_responses = 1
```

## Expected Result

```
net.ipv4.icmp_ignore_bogus_error_responses = 1
```

## Remediation

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

```
net.ipv4.icmp_ignore_bogus_error_responses = 1
```

Run the following commands to set the active kernel parameters:

```bash
sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1
sysctl -w net.ipv4.route.flush=1
```

## Default Value

Not specified.

## 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