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cis-ubuntu1204-v110-7-1-1

DevOps & Security
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Disable IP Forwarding

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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-v110-7-1-1/SKILL.md

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7.1.1 Disable IP Forwarding (Scored)

Profile Applicability

  • Level 1

Description

The net.ipv4.ip_forward flag is used to tell the server whether it can forward packets or not. If the server is not to be used as a router, set the flag to 0.

Rationale

Setting the flag to 0 ensures that a server with multiple interfaces (for example, a hard proxy), will never be able to forward packets, and therefore, never serve as a router.

Audit Procedure

Using Command Line

Perform the following to determine if net.ipv4.ip_forward is enabled on the system.

/sbin/sysctl net.ipv4.ip_forward

Expected Result

net.ipv4.ip_forward = 0

Remediation

Using Command Line

Set the net.ipv4.ip_forward parameter to 0 in /etc/sysctl.conf:

net.ipv4.ip_forward=0

Modify active kernel parameters to match:

/sbin/sysctl -w net.ipv4.ip_forward=0
/sbin/sysctl -w net.ipv4.route.flush=1

Default Value

IP forwarding is disabled by default.

References

  • CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Scored