Linux Boot with No Networking

I recently wanted to install an M.2 NVMe to PCIe 4.0 X4 Adapter on an existing server. The idea was to install a new NVMe SSD drive, and the motherboard had no more M.2 sockets available.

The server is running Proxmox with Linux Kernel 6.8.12. I thought this should be a 15-minute exercise. How wrong I was. After installing all the hardware, the system booted up but there was no networking access. This was especially painful because I could no longer remote into the server. I had to go pull out an old monitor and keyboard and perform diagnostics.

I used the journalctl command to diagnose the issue, and found the following entry:

Feb 01 13:36:21 pvproxmox networking[1338]: error: vmbr0: bridge port enp6s0 does not exist
Feb 01 13:36:21 pvproxmox networking[1338]: warning: vmbr0: apply bridge ports settings: bridge configuration failed (missing ports)
Feb 01 13:36:21 pvproxmox /usr/sbin/ifup[1338]: error: vmbr0: bridge port enp6s0 does not exist
Feb 01 13:36:21 pvproxmox /usr/sbin/ifup[1338]: warning: vmbr0: apply bridge ports settings: bridge configuration failed (missing ports)

The above error message indicates that enp6s0 no longer exists. When I looked at earlier messages, I noticed this one:

Feb 01 13:36:15 pvproxmox kernel: r8169 0000:07:00.0 enp7s0: renamed from eth0

It looks like the interface name has been changed from enp6s0 to enp7s0. Therefore the correct remedy is to edit the /etc/network/interfaces to reflect the name change. Below is the new content of the file.

# cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface enp7s0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.188.2/24
        gateway 192.168.188.1
        bridge-ports enp7s0
        bridge-stp off
        bridge-fd 0

iface wlp5s0 inet manual

This would be very annoying if the old interface name was used in many other configuration files. There is one other reference that I found on the Internet (https://www.baeldung.com/linux/rename-network-interface) detailing a way to change the network interface name using the udev rules. I did not try this, but something to keep in mind in the future.

In a previous post and on another home server, I did fix the name using netplan, but Proxmox is not using it.