If you’re hosting Proxmox VE on a server with only one public IP, you can still create a private virtual network with NAT and DHCP for your VMs using a Linux bridge.

This guide shows how to set up a Proxmox bridge (vmbr0) and run a DHCP server for VMs using a private subnet like 192.168.1.0/24.

🌐 1. Configure Proxmox Bridge (vmbr0)

Edit your host’s network config (Debian-style /etc/network/interfaces) and add the setup for vmbr0 at the end, along with iptables for routing.

auto vmbr0
iface vmbr0 inet static
    address 192.168.1.1/24
    bridge_ports none
    bridge_stp off
    bridge_fd 0
    post-up   iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o enp0s31f6 -j MASQUERADE
    post-down iptables -t nat -D POSTROUTING -s 192.168.1.0/24 -o enp0s31f6 -j MASQUERADE

Enable IP forwarding:

echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf
sysctl -p

And then restart networking:

systemctl restart networking

🧭 2. Install DHCP Server

Install ISC DHCP server:

Install ISC DHCP server using the package isc-dhcp-server with your distribution of choice. In Debian case we can use:

apt install isc-dhcp-server -y

Edit /etc/default/isc-dhcp-server to bind to vmbr0:

INTERFACESv4="vmbr0"

Configure DHCP settings in /etc/dhcp/dhcpd.conf:

subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.100 192.168.1.200;
  option routers 192.168.1.1;
  option domain-name-servers 1.1.1.1, 8.8.8.8;
  default-lease-time 600;
  max-lease-time 7200;
}

Start the DHCP service:

systemctl enable --now isc-dhcp-server