<!-- Copyright (c) 2026 defconxt. All rights reserved. -->
<!-- Licensed under AGPL-3.0 — see LICENSE file for details. -->
---
name: implementing-endpoint-network-segmentation
description: >-
  Design and enforce network segmentation at the endpoint level using host-based firewalls and micro-segmentation to limit lateral movement.
domain: cybersecurity
subdomain: endpoint-security
tags:
  - segmentation
  - micro-segmentation
  - host-firewall
  - zero-trust
  - lateral-movement
version: "1.0"
author: defconxt
license: AGPL-3.0
metadata:
  mitre-attack: ["T1021"]
---

# Implementing Endpoint Network Segmentation

## Overview

Endpoint network segmentation restricts which systems can communicate with
each other at the host level. By enforcing least-privilege network access on
each endpoint, segmentation limits lateral movement during breaches and reduces
blast radius.

## Prerequisites

| Requirement | Install |
|---|---|
| Host-based firewall | Windows Firewall, iptables, or pf |
| MDM / GPO | Policy deployment mechanism |
| Network flow data | Baseline communication patterns |
| Python 3.10+ | For agent tooling |

## Key Concepts

### Segmentation Approaches

- **Host-based firewall** — Windows Firewall rules via GPO/Intune
- **Micro-segmentation** — Agent-based (Illumio, Guardicore)
- **ZTNA** — Identity-aware access replacing network-level trust
- **IPsec isolation** — Domain/server isolation via IPsec policies

### Policy Design

1. **Discover** — Map actual communication flows
2. **Label** — Classify endpoints by role
3. **Design** — Define allowed flows per label pair
4. **Test** — Deploy in audit/monitor mode
5. **Enforce** — Switch to blocking mode

### Critical Rules

- Workstation-to-workstation: **deny**
- Workstation-to-server: **allow specific ports only**
- Admin-to-management: **allow with MFA**
- Server-to-internet: **deny** (except explicit proxy)
- Default: **deny all**

## Workflow

1. **Map communication flows** — capture network connections per endpoint role
2. **Classify endpoints** — label by function (workstation, server, admin, IoT)
3. **Design segmentation policy** — define allowed flows per classification pair
4. **Deploy in monitor mode** — enable logging without blocking
5. **Analyze violations** — review blocked-if-enforced traffic for policy gaps
6. **Enforce policies** — switch from monitor to enforcement mode
7. **Monitor and tune** — continuously review blocks and adjust policies

## Quick Reference

```bash
# Run the agent
node scripts/agent.js analyze --target <scope>
node scripts/agent.js report --target <scope>
```

## Detection

```yaml
title: Endpoint Network Segmentation Detection
id: 2b053e8e-ff71-43a8-a54a-91ab558225cf
status: experimental
description: Detects suspicious activity related to implementing endpoint network segmentation techniques in endpoint security context
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    CommandLine: "*implementing*endpoint*"
  condition: selection
level: medium
tags:
  - attack.t1021
  - attack.execution
falsepositives:
  - Endpoint management software performing routine maintenance tasks
```

## Verification

| Check | Method |
|---|---|
| Flows mapped | Communication baseline captured for 30-day period |
| Labels assigned | All endpoints classified by role |
| Monitor mode active | Policies deployed in audit mode, violations logged |
| Enforcement enabled | Blocking rules active, unauthorized flows denied |
| Lateral movement blocked | Workstation-to-workstation traffic denied |

## References

- [NIST SP 800-125B](https://csrc.nist.gov/)
- [CIS Control 12](https://www.cisecurity.org/controls)
- [Microsoft — Windows Firewall](https://learn.microsoft.com/en-us/windows/security/operating-system-security/network-security/windows-firewall/)
- [NIST SP 800-207 — Zero Trust](https://csrc.nist.gov/pubs/sp/800/207/final)
