Troubleshooting your network - 1Copenut/homelab-learning GitHub Wiki

I often have to look up the same commands for troubleshooting. These include where and how to bring network interface cards (NICs) up on startup. Hopefully having these things written down will save someone some time and effort.

Finding and enabling NICs

The first file to check for NICs is /etc/network/interfaces. It should list all of the NICs installed on your machine, and in the case of ProxMox, any virtual bridges it contains.

Installed NICs

If you have more than one NIC installed, you may need to ensure they auto-start. Look for a line that starts with iface. This should be your NIC. Add the following line just above each interface:

auto IFACE_NAME 

After adding these auto-start declarations, go back to the Proxmox web interface. Navigtate to Datacenter > Node > System > Network. All NICs should be listed and should say Active: Yes and Autostart: Yes.

Proxmox virtual bridges

The ProxMox virtual bridge vmbr0 should have been created when you installed the hypervisor. The basic definition should look like this:

# /etc/network/interfaces

After adding the 

auto vmbr0
iface vmbr0 inet static
        address # static IP in a local network range such as 192.168.100.2/24
        gateway # static IP such as 192.168.100.1
        bridge-ports # should match the first NIC listed
        bridge-stp off
        bridge-fd 0