// the problem
Why This Needed to Exist
Most IT and cybersecurity professionals rely on theoretical knowledge without hands-on infrastructure experience. Cloud labs are expensive and don't replicate the physical networking challenges of real enterprise environments. I needed a way to practice real infrastructure management — firewall configuration, VLAN routing, VPN tunnels, and server administration — on physical hardware, with the same complexity as a production network.
// what i built
The Solution
I built a full-scale virtualization lab on a Dell PowerEdge T440 server running Proxmox VE 8.1. The lab hosts multiple virtual machines including a pfSense firewall, Ubuntu Server, Windows Domain Controller, and Kali Linux — all connected through virtual bridge interfaces with VLAN segmentation. The architecture mirrors a small enterprise network with DMZ, internal, and management zones.
// the architecture
System Design
SERVER: Dell PowerEdge T440 (Tower)
CPU: Intel Xeon Silver 4110 (8C/16T @ 2.10-4.00 GHz)
RAM: 32 GB ECC DDR4 (2x16 GB Micron @ 2400 MHz)
Storage: 6x ~440 GB SAS SSDs (PERC H730 RAID)
NICs: 2x Ethernet | iDRAC Remote Mgmt
HYPERVISOR: Proxmox VE (KVM/QEMU)
Nested Virtualization: Enabled
NETWORK TOPOLOGY:
Internet -> ISP Router -> Dell T440 (Proxmox VE)
|- vmbr0 (10.0.0.1/24) - Management LAN
| |- VM100: pfSense Firewall
| |- VM101: Ubuntu Server (DNS/DHCP)
|- vmbr1 (10.0.1.1/24) - DMZ VLAN
| |- VM102: Windows Domain Controller
|- Tailscale Overlay Network
| |- 100.64.0.1: homelab (direct)
| |- 100.64.0.2: laptop (relay)
|- VM103: Kali Linux (Security Testing)
USE CASES:
- Network labs (VLANs, firewall rules, inter-VLAN routing)
- VPN services (Tailscale, OpenVPN)
- CCNA / security practice environments
- Server administration labs// the hardware
Server Specifications
Dell PowerEdge T440
Tower form factor · iDRAC remote management
Intel Xeon Silver 4110
8 cores / 16 threads · 2.10–4.00 GHz · VT-x, VT-d enabled
32 GB ECC DDR4
2×16 GB Micron DIMMs · Dual-rank · 2400 MHz
~2.6 TB SAS SSDs
6× ~440 GB hot-swap drives · PERC H730 RAID controller
2× Ethernet NICs
VLANs · pfSense · Tailscale VPN · OpenVPN
Proxmox VE
KVM/QEMU · Nested virtualization confirmed
// key challenges
Problems I Solved
Double NAT Without DMZ Access
My ISP router didn't support DMZ or bridge mode, creating a double NAT situation that blocked inbound connections. I implemented Tailscale as a WireGuard-based overlay network, creating encrypted point-to-point tunnels that bypass NAT entirely. This gives me full remote access to every lab service from my laptop without exposing any ports to the public internet.
VLAN Routing Between Virtual Bridges
Proxmox virtual bridges don't natively route between VLANs. I configured pfSense as the inter-VLAN router with specific firewall rules allowing controlled traffic flow between the management LAN and DMZ — mimicking how a real enterprise firewall handles zone-based security.
DNS Resolution Across VLAN Segments
VMs in different VLANs couldn't resolve hostnames. I set up the Ubuntu Server as a central DNS resolver with zone files for each VLAN, and configured pfSense to forward DNS queries to it — establishing proper name resolution across the entire lab.
// outcomes
What I Learned
This lab gave me practical experience that directly maps to enterprise job requirements: configuring firewall rules on pfSense, managing VLANs and inter-VLAN routing, setting up VPN tunnels for remote access, and administering both Linux and Windows servers. I can now confidently discuss network architecture decisions in interviews with specific examples from a real working environment.
// tech stack
Tools & How I Used Them
Dell PowerEdge T440
Tower server with Xeon Silver 4110, 32 GB ECC DDR4, SAS SSDs, iDRAC remote management
Proxmox VE
Type-1 hypervisor with KVM/QEMU backend and nested virtualization support
pfSense
Primary firewall handling VLAN routing, DNS forwarding, and access control
Tailscale
WireGuard-based mesh VPN bypassing double NAT for secure remote access
VLANs
802.1Q network segmentation into Management, DMZ, and Testing zones
Ubuntu Server
DNS/DHCP server providing name resolution and IP management across VLANs