Network Configuration

Network settings on a Proxmox node — bridges for VMs/CTs, DNS, and useful CLI checks.

1. Key files

File	Purpose
`/etc/network/interfaces`	Main network config (bridges, VLANs, IPs)
`/etc/resolv.conf`	DNS resolvers
`/etc/hosts`	Local hostname resolution

View current config:

cat /etc/network/interfaces
cat /etc/resolv.conf
cat /etc/hosts

Apply changes after editing interfaces:

ifreload -a
# or
systemctl restart networking

2. Bridge basics

Proxmox uses Linux bridges (e.g. vmbr0) so VMs and containers share the host’s physical NIC.

Typical /etc/network/interfaces snippet:

auto lo
iface lo inet loopback

auto eno1
iface eno1 inet manual

auto vmbr0
iface vmbr0 inet static
    address 192.168.1.10/24
    gateway 192.168.1.1
    bridge-ports eno1
    bridge-stp off
    bridge-fd 0

Directive	Meaning
`bridge-ports eno1`	Attach physical NIC to the bridge
`bridge-stp off`	Disable Spanning Tree on lab/single-switch setups
`bridge-fd 0`	Forwarding delay — 0 for immediate forwarding

3. VLAN-aware bridge

When the Proxmox host connects to a Cisco switch via a 802.1Q trunk, configure the physical port as manual (no IP on the raw NIC) and enable VLAN filtering on the bridge. The bridge then acts as a virtual trunk switch — VMs and CTs receive traffic tagged on the VLAN you assign per NIC.

3.1 `/etc/network/interfaces` example

auto lo
iface lo inet loopback

# The physical port connected to your working expansion network card
iface enp2s0 inet manual

# The VLAN-Aware Bridge (Acts as your virtual Trunk Switch)
auto vmbr0
iface vmbr0 inet manual
        bridge-ports enp2s0
        bridge-stp off
        bridge-fd 0
        bridge-vlan-aware yes
        bridge-vids 2-4094

# The explicit Proxmox Management interface tagged on VLAN 99
auto vmbr0.99
iface vmbr0.99 inet static
        address 192.168.99.10/24
        gateway 192.168.99.1

3.2 What each block does

Block	Role
`iface enp2s0 inet manual`	Physical NIC carries tagged frames only — no IP assigned directly on the port
`vmbr0` + `bridge-vlan-aware yes`	Bridge behaves as a VLAN-aware switch; filters traffic by VLAN ID
`bridge-vids 2-4094`	VLAN range the bridge accepts and forwards (adjust to your lab)
`vmbr0.99`	Host management IP on VLAN 99 — Proxmox web UI and SSH use this address

The upstream Cisco port must be configured as a trunk allowing the same VLANs (including VLAN 99 for management).

4. CLI diagnostics

ip link show                  # interfaces and state
ip addr show                  # IP addresses
ip route show                 # routing table
bridge link show              # bridge member ports
ping -c 3 192.168.1.1         # test gateway
dig proxmox.local             # test DNS resolution
ss -tlnp                      # listening ports (22, 8006, etc.)

Proxmox web UI listens on TCP 8006 by default.

5. Firewall (if enabled)

Proxmox includes a host-level firewall (Datacenter → Firewall in the UI).

pve-firewall status
pve-firewall compile          # show generated rules

For homelab setups, firewall rules are often disabled on the node and handled upstream on the Cisco core switch.