DHCP Server Configuration Template

A production-ready DHCP server configuration template for classroom deployments using MindSpark servers with UniFi U7 Lite Access Points.

Overview

This template provides a standardized DHCP configuration for offline classroom environments, supporting 60-100 learner devices accessing educational content through tablets and other mobile devices.

Network Specifications

• Network Range: 192.168.8.0/24
• Server/Gateway IP: 192.168.8.200
• DHCP Pool: 192.168.8.101 - 192.168.8.200 (100 addresses)
• Access Point IP: 192.168.8.10 (static)
• Client Capacity: 60-100 devices

Prerequisites

• ISC DHCP Server (isc-dhcp-server package)
• Ubuntu/Debian-based Linux system
• UniFi U7 Lite Access Point (or compatible)
• Network interface configured on 192.168.8.0/24 subnet

Installation

1. Install DHCP Server

sudo apt update
sudo apt install isc-dhcp-server

2. Deploy Configuration

# Backup existing configuration
sudo cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.backup

# Copy template configuration
sudo cp dhcp.conf /etc/dhcp/dhcpd.conf

3. Configure Network Interface

Edit /etc/default/isc-dhcp-server and set the interface:

INTERFACESv4="eth0"  # Replace with your interface name

4. Update Access Point MAC Address

Edit /etc/dhcp/dhcpd.conf and replace the MAC address in the static assignment section:

host unifi-ap {
    hardware ethernet 84:78:48:86:06:d5;  # Replace with your AP's MAC
    fixed-address 192.168.8.10;
}

5. Start DHCP Service

# Enable and start the service
sudo systemctl enable isc-dhcp-server
sudo systemctl start isc-dhcp-server

# Check status
sudo systemctl status isc-dhcp-server

Configuration Details

Lease Times

• Default Lease: 6 hours (21600 seconds)
• Maximum Lease: 12 hours (43200 seconds)

These values are optimized for classroom sessions while preventing IP exhaustion.

DNS Configuration

The template uses public DNS servers (Google DNS and Cloudflare):

• Primary: 8.8.8.8
• Secondary: 1.1.1.1

For fully offline deployments, you may want to configure local DNS or remove these entries.

IP Address Allocation

Range	Purpose
192.168.8.1 - 192.168.8.100	Reserved for servers, APs, and infrastructure
192.168.8.101 - 192.168.8.200	DHCP pool for client devices
192.168.8.201 - 192.168.8.254	Available for future expansion

Customization

Adding More Static Assignments

To add additional devices with static IPs, add entries outside the DHCP range:

host device-name {
    hardware ethernet AA:BB:CC:DD:EE:FF;
    fixed-address 192.168.8.20;
}

Adjusting Client Capacity

To support more devices, expand the DHCP range:

range 192.168.8.101 192.168.8.250;  # Supports 150 devices

Changing Network Subnet

If using a different subnet, update all IP addresses accordingly and ensure consistency across:

• Subnet declaration
• Gateway (router) option
• Broadcast address
• DHCP range
• Static assignments

Troubleshooting

Check DHCP Server Status

sudo systemctl status isc-dhcp-server

View DHCP Logs

sudo journalctl -u isc-dhcp-server -f

Test Configuration Syntax

sudo dhcpd -t -cf /etc/dhcp/dhcpd.conf

View Active Leases

cat /var/lib/dhcp/dhcpd.leases

Common Issues

Service fails to start:

• Check configuration syntax with dhcpd -t
• Verify network interface is correctly set
• Ensure no other DHCP server is running on the network

Clients not receiving IPs:

• Verify DHCP range doesn't overlap with static assignments
• Check firewall rules (UDP ports 67-68)
• Ensure server IP is within the subnet range

Hardware Compatibility

Tested With

• Server: MindSpark offline education servers
• Access Point: UniFi U7 Lite
• Clients: Android tablets, iOS devices, laptops

Known Compatible Access Points

• UniFi U7 Lite (primary)
• UniFi U6 series
• Other UniFi APs (requires MAC address update)

Security Considerations

• This configuration is designed for isolated classroom networks
• No DHCP authentication is configured (suitable for trusted environments)
• For internet-connected deployments, consider additional security measures
• Regularly review active leases for unauthorized devices

Contributing

When contributing improvements to this template:

1. Test configuration in a classroom environment
2. Maintain clear documentation in comments
3. Follow the existing formatting style
4. Update this README with any new features

License

This configuration template is provided as-is for educational deployment use.

Support

For issues specific to:

• DHCP Configuration: Check the inline comments in dhcp.conf
• UniFi Access Points: Refer to Ubiquiti documentation
• MindSpark Servers: Contact Edulution support

Version History

• v1.0 - Initial template for MindSpark classroom deployments
• Supports 60-100 clients with UniFi U7 Lite AP

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Maintained by: Edulution
Last Updated: November 2025