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AtlasOS includes networking tweaks that apply optimized network configurations and enhance network security. These tweaks are defined in YAML configuration files located in Configuration/tweaks/networking/.

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Overview

Networking tweaks in AtlasOS focus on:
  • Applying optimized network settings
  • Disabling vulnerable protocols
  • Restricting anonymous network access
  • Optimizing SMB/CIFS file sharing
  • Enhancing network security

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Network Configuration

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Atlas Network Settings

---
title: Applies Atlas' Network Settings
description: Applies Atlas' optimised network settings
actions:
  - !cmd:
    command: '"AtlasDesktop\9. Troubleshooting\Network\Reset Network to Atlas Default.cmd" /silent'
    exeDir: true
    wait: true
    runas: currentUserElevated
This tweak applies AtlasOS’s optimized network configuration by executing a script that resets and configures network settings to Atlas defaults. The configuration includes optimizations for:
  • Network adapter settings
  • TCP/IP parameters
  • DNS configuration
  • Network performance tuning

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Protocol Security

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Disable LLMNR Protocol

---
title: Disable LLMNR Protocol
description: Disable Link-Local Multicast Name Resolution (LLMNR) protocol as it is vulnerable and has been replaced by DNS
actions:
  # https://admx.help/?Category=Windows_11_2022&Policy=Microsoft.Policies.DNSClient::Turn_Off_Multicast
  - !registryValue:
    path: 'HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient'
    value: 'EnableMulticast'
    data: '0'
    type: REG_DWORD
LLMNR (Link-Local Multicast Name Resolution) is disabled because:
  • Security vulnerability: Susceptible to man-in-the-middle attacks
  • Credential theft: Can be exploited to capture authentication credentials
  • Obsolete: Replaced by modern DNS resolution
  • Network pollution: Generates unnecessary multicast traffic
Attack scenario: Attackers can respond to LLMNR queries and capture NTLM hashes, which can then be cracked or relayed.

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SMB/File Sharing Security

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Restrict Anonymous Enumeration of Shares

---
title: Restrict Anonymous Enumeration of Shares
description: Restricts anonymous enumeration of shares
actions:
  # https://www.stigviewer.com/stig/microsoft_windows_10/2022-04-08/finding/V-220930
  - !registryValue:
    path: 'HKLM\SYSTEM\CurrentControlSet\Control\Lsa'
    value: 'RestrictAnonymous'
    data: '1'
    type: REG_DWORD
Prevents anonymous users from enumerating network shares, protecting against:
  • Information disclosure
  • Reconnaissance attacks
  • Unauthorized access attempts
Security Standard: Implements DISA STIG finding V-220930 for Windows 10/11.

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Restrict Anonymous Share Access

Further restricts anonymous access to network shares beyond enumeration, preventing:
  • Anonymous connections to shared resources
  • Null session attacks
  • Unauthorized data access

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Disable SMB Bandwidth Throttling

Removes bandwidth limitations on SMB (Server Message Block) file transfers for improved file sharing performance over local networks.

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Configuration Location

All networking tweak YAML files are located in: 
src/playbook/Configuration/tweaks/networking/
├── atlas-network-settings.yml
├── disable-llmnr.yml
└── shares/
    ├── disable-smb-bandwidth-throttling.yml
    ├── restrict-anonymous-access.yml
    └── restrict-anonymous-enumeration.yml

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Networking Tweaks Summary

TweakPurposeSecurity ImpactPerformance Impact
Atlas Network SettingsOptimize network configurationMediumHigh
Disable LLMNRPrevent credential theftHighNone
Restrict Anonymous EnumerationBlock share discoveryHighNone
Restrict Anonymous AccessBlock share accessHighNone
Disable SMB ThrottlingImprove transfer speedNoneHigh

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Security Standards Compliance

AtlasOS networking tweaks implement DISA STIG findings:

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V-220930: Anonymous Share Enumeration

Severity: Medium
Vulnerability: Allows anonymous users to enumerate network shares
Fix: Set RestrictAnonymous to 1 SAM account enumeration restriction (covered in Security Tweaks)

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Network Protocol Security

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Disabled Protocols

  • LLMNR (Link-Local Multicast Name Resolution)
    • Port: UDP 5355
    • Vulnerability: NTLM hash capture
    • Replacement: DNS
    • Status: Disabled
For enhanced security, also consider disabling:
  • NetBIOS over TCP/IP (if not needed)
  • SMBv1 (already disabled in modern Windows)
  • IPv6 (if not used on your network)
These are typically handled by the Atlas network reset script.

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SMB/CIFS Optimizations

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File Sharing Performance

AtlasOS optimizes SMB file sharing by:
  1. Removing Bandwidth Throttling
    • Allows full network speed utilization
    • Improves large file transfer times
    • Benefits local network file sharing
  2. Security Restrictions
    • Blocks anonymous access
    • Prevents information disclosure
    • Maintains authenticated share access

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SMB Security Features

AtlasOS maintains these SMB security features:
  • SMBv2/v3 encryption support
  • Authenticated access requirements
  • Share access control lists (ACLs)
  • Anonymous access restrictions

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Network Configuration Details

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Registry Modifications

Networking tweaks modify these registry locations: 
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient
└── EnableMulticast: 0 (LLMNR disabled)

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
├── RestrictAnonymous: 1 (enumeration blocked)
└── RestrictAnonymousSAM: 1 (from security tweaks)

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Atlas Network Reset Script

The Atlas network reset script performs:
  • Network adapter reset
  • TCP/IP stack optimization
  • DNS cache flush
  • Winsock reset
  • Network settings optimization
  • Protocol configuration
Location: AtlasDesktop\9. Troubleshooting\Network\Reset Network to Atlas Default.cmd

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Performance Considerations

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Local Network

  • Disabled SMB throttling improves LAN transfer speeds
  • Optimized TCP/IP settings reduce latency
  • DNS configuration improves name resolution

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Internet Connection

  • TCP window scaling optimization
  • Receive Window Auto-Tuning
  • Congestion control algorithms

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YAML Structure

Networking tweaks use these action types: 
---
title: Network Tweak Name
description: What the networking tweak does
actions:
  # Registry modification
  - !registryValue:
    path: 'HKLM\Path\To\Network\Key'
    value: 'SettingName'
    data: '0'
    type: REG_DWORD
  
  # Execute network configuration script
  - !cmd:
    command: 'network-config-script.cmd /silent'
    exeDir: true
    wait: true
    runas: currentUserElevated

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Reverting Network Tweaks

reg delete "HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" /v EnableMulticast /f

reg add "HKLM\SYSTEM\CurrentControlSet\Control\Lsa" /v RestrictAnonymous /t REG_DWORD /d 0 /f

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Reset Network to Windows Default

Windows includes built-in network reset: 
Settings > Network & Internet > Advanced network settings > Network reset
Or via command line: 
netsh winsock reset
netsh int ip reset
netsh advfirewall reset
ipconfig /release
ipconfig /renew
ipconfig /flushdns

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Best Practices

  • Keep LLMNR disabled for security
  • Maintain anonymous access restrictions
  • Use the Atlas network reset for optimal settings
  • Enable SMB encryption for sensitive data transfers
  • Regularly update network drivers
  • Monitor network performance after applying tweaks

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Troubleshooting

If you experience network issues after applying tweaks:
  1. Run Atlas Network Reset
    • Location: AtlasDesktop\9. Troubleshooting\Network
    • Restores Atlas default configuration
  2. Check Network Adapter
    • Update drivers
    • Verify adapter is enabled
    • Check physical connection
  3. DNS Issues
    • Flush DNS cache: ipconfig /flushdns
    • Try alternative DNS servers (1.1.1.1, 8.8.8.8)
  4. File Sharing Issues
    • Verify SMB services are running
    • Check firewall rules
    • Ensure correct credentials for share access

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