Tutorial 2: Layer PXE onto an Existing DHCP Network
⏱ Time: 10 minutes ｜ Level: Intermediate ｜ Audience: You already have a DHCP server on your network and want to add network boot Prerequisites: PxeLab is running (see Getting Started), a computer that supports network boot, and Layer-2 connectivity between the client and PxeLab
The Scenario
Your company network already has a DHCP server (e.g., the gateway at 192.168.1.1 doubles as one), and all devices are online. You want to add PXE network boot to the network — say, to install systems on a few machines — without touching the existing DHCP or disturbing any devices.
That's exactly what proxy mode is for: IP addresses are still assigned by the existing DHCP server; PxeLab only supplies the PXE boot information.
Existing DHCP (192.168.1.1) PxeLab (192.168.1.100)
│ │
├─ assigns IP ──► client ◄── boot info (proxy, port 4011)Preparation
- PxeLab server IP (example:
192.168.1.100), on the same Layer-2 network as the clients (proxy relies on broadcasts; cross-VLAN requires DHCP relay) - Your existing subnet (example:
192.168.1.0/24) - A client that supports PXE network boot
Step 1: Add an interface and choose proxy mode
Go to Basic Config → Service Config → DHCP, click Add Interface in the top-right corner, and fill in:
| Field | Example value |
|---|---|
| Interface name | eth0 (or pick a detected NIC from the list) |
| IP address | 192.168.1.100 (the PxeLab server's IP) |
| Subnet 1 → Subnet CIDR | 192.168.1.0/24 (your existing subnet) |
| Subnet 1 → DHCP mode | proxy (Proxy DHCP) |
Leave address pool, gateway, and DNS empty — proxy mode doesn't assign IPs, so these fields are not needed (the UI will tell you).
Save.
Step 2: Make sure ProxyDHCP is running
Check the service status bar at the top: ProxyDHCP (port 4011) should show "running"; if not, start it.
Step 3: Boot the client and enter network boot
Power the client on, enter its boot menu (F12 / F11 / Esc), and choose network boot.
Boot now has two cooperating sources:
- The existing DHCP server assigns the client its IP
- PxeLab supplies the boot file location and boot information
If all is well, the PxeLab boot menu appears within a few seconds — from here on, the flow is identical to Tutorial 1 (pick the OS Install Catalog, install, etc.).
Step 4: Verify
- The client got an IP (from the existing DHCP) and the PxeLab boot menu appeared — both together mean success
- Everything else on the network keeps working as before (proxy mode ignores non-PXE clients)
Common issues in this tutorial
| Symptom | Likely cause | Fix |
|---|---|---|
| Client gets an IP but no boot menu | Layer-2 unreachable / UDP 4011 blocked | Confirm client and PxeLab are on the same subnet; allow UDP 67/4011 |
| No menu, and PXE option conflict on DHCP | The existing DHCP also serves PXE options | Disable PXE/boot options on the existing DHCP (keep IP assignment) |
| No response from clients across VLANs | Proxy mode relies on broadcasts | Configure DHCP relay on the switch/router for the client subnet, pointing to PxeLab |
Going further
- Protocol differences between proxy and server (Option 60, yiaddr=0 recognition): see DHCP Modes
- The full install flow: Tutorial 1: Install Ubuntu on a Bare Metal Machine