Small Office DHCP and DNS Audit Toolkit with PowerShell

Expected Outcome

A working toolkit that allows for auditing DHCP leases and DNS records, with the ability to export lease conflict checks to a CSV file.

Assumptions

• Windows Server with DHCP and DNS roles installed
• PowerShell access with administrative privileges
• Basic understanding of DHCP and DNS concepts

Bill of Materials

• Windows Server 2016 or later
• PowerShell ISE or any text editor
• CSV file for exporting results

Build Steps

1. Set Up PowerShell Environment

   Ensure that PowerShell is configured to run scripts on your server.

   Changes system state: review before running

   Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

2. Create DHCP Lease Check Script

   Develop a PowerShell script that retrieves DHCP lease information.

   Safe to run: read-only

   $DhcpServer = 'YourDhcpServerName'
   $Leases = Get-DhcpServerv4Lease -ComputerName $DhcpServer
   $Leases | Export-Csv -Path 'C:\DHCPLeases.csv' -NoTypeInformation

3. Create DNS Records Check Script

   Develop a PowerShell script that retrieves DNS records.

   Safe to run: read-only

   $DnsServer = 'YourDnsServerName'
   $DnsRecords = Get-DnsServerResourceRecord -ComputerName $DnsServer -ZoneName 'YourDomain.com'
   $DnsRecords | Export-Csv -Path 'C:\DNSRecords.csv' -NoTypeInformation

4. Create Lease Conflict Check Script

   Develop a PowerShell script to check for lease conflicts.

   Safe to run: read-only

   $ConflictLeases = Get-DhcpServerv4Lease -ComputerName $DhcpServer | Where-Object { $_.State -eq 'Conflict' }
   $ConflictLeases | Export-Csv -Path 'C:\LeaseConflicts.csv' -NoTypeInformation

5. Test the Scripts

   Run the scripts to ensure they work correctly and generate the expected output.

   Safe to run: read-only

   powershell -File 'C:\PathToYourScript\DhcpLeaseCheck.ps1'
   powershell -File 'C:\PathToYourScript\DnsRecordsCheck.ps1'
   powershell -File 'C:\PathToYourScript\LeaseConflictCheck.ps1'

6. Schedule Regular Audits

   Set up a scheduled task to run the scripts at regular intervals.

   Changes system state: review before running

   New-ScheduledTask -Action (New-ScheduledTaskAction -Execute 'powershell.exe' -Argument '-File C:\PathToYourScript\DhcpLeaseCheck.ps1') -Trigger (New-ScheduledTaskTrigger -Daily -At '2:00AM') -Principal (New-ScheduledTaskPrincipal -UserId 'SYSTEM' -LogonType ServiceAccount) | Register-ScheduledTask -TaskName 'DHCP Lease Check'

Validation

• Verify that the CSV files are created and contain the expected data.
• Check for any errors in the PowerShell console during script execution.

Troubleshooting

• If a step fails, capture the exact command, exit code, and log line before retrying or changing the design.
• Check route tables, DNS resolution, firewall rules, and peer status from both sides of the connection.

Cleanup or Rollback

• Keep a copy of working configuration, compose files, scripts, and service credentials before removing containers, packages, or data directories.
• Export current network, DNS, VPN, and firewall settings before changing routes, peers, or resolver configuration.
• Rollback by restoring the prior route, peer, DNS, or firewall configuration and restarting only the affected service.

Next Improvements

• Integrate additional checks for other network services.
• Create a user-friendly interface for the toolkit.