[SOLVED] Changing routers, what network interface changes are needed?

mikeebee · Dec 11, 2022

Hello all,

I recently changed routers, I lost my connection to Promox (via SSH or the Web UI). From my research, I think I understand what changes I need to make but I'd like to double-check with you before I take action as I'm nervous I'll completely lose access (I can still plug my old router in to access it currently).

Here is my original network setup

(I need to plug all this back in, to access Proxmox)

Code:

Subnet mask: 255.255.255.0
Router: 192.168.1.1

Here is my new network setup

It's an Eero 6+ mesh router. It has IPv6 enabled (The default setup).

Code:

Subnet mask: 255.255.252.0
Router: 192.168.4.1

This is the output of nano etc/network/interfaces

Code:

auto lo
iface lo inet loopback

iface enp4s0 inet manual

auto vmbr0
iface vmbr0 inet static
    address 192.168.1.115
    netmask 255.255.255.0
    gateway 192.168.1.1
    bridge_ports enp4s0
    bridge_stp off
    bridge_fd 0

iface eno2 inet manual

This is the output of nano etc/hosts

Code:

127.0.0.1 localhost.localdomain localhost
192.168.1.115 mb1.local mb1

# The following lines are desirable for IPv6 capable hosts

::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

Setup info

Not sure you'll need all this but here is the output from pveversion -v

Code:

proxmox-ve: 6.2-2 (running kernel: 5.4.65-1-pve)
pve-manager: 6.2-12 (running version: 6.2-12/b287dd27)
pve-kernel-5.4: 6.2-7
pve-kernel-helper: 6.2-7
pve-kernel-5.4.65-1-pve: 5.4.65-1
pve-kernel-5.4.34-1-pve: 5.4.34-2
ceph-fuse: 12.2.11+dfsg1-2.1+b1
corosync: 3.0.4-pve1
criu: 3.11-3
glusterfs-client: 5.5-3
ifupdown: 0.8.35+pve1
ksm-control-daemon: 1.3-1
libjs-extjs: 6.0.1-10
libknet1: 1.16-pve1
libproxmox-acme-perl: 1.0.5
libpve-access-control: 6.1-3
libpve-apiclient-perl: 3.0-3
libpve-common-perl: 6.2-2
libpve-guest-common-perl: 3.1-3
libpve-http-server-perl: 3.0-6
libpve-storage-perl: 6.2-8
libqb0: 1.0.5-1
libspice-server1: 0.14.2-4~pve6+1
lvm2: 2.03.02-pve4
lxc-pve: 4.0.3-1
lxcfs: 4.0.3-pve3
novnc-pve: 1.1.0-1
proxmox-backup-client: 0.9.0-2
proxmox-mini-journalreader: 1.1-1
proxmox-widget-toolkit: 2.3-1
pve-cluster: 6.2-1
pve-container: 3.2-2
pve-docs: 6.2-6
pve-edk2-firmware: 2.202002-1
pve-firewall: 4.1-3
pve-firmware: 3.1-3
pve-ha-manager: 3.1-1
pve-i18n: 2.2-1
pve-qemu-kvm: 5.1.0-3
pve-xtermjs: 4.7.0-2
qemu-server: 6.2-15
smartmontools: 7.1-pve2
spiceterm: 3.1-1
vncterm: 1.6-2
zfsutils-linux: 0.8.4-pve2

Next steps

Assuming I don't need to change the IP address I currently use to access Proxmox (192.168.1.115) do I just need to change the netmask and gateway in etc/network/interfaces to this?

Code:

netmask 255.255.252.0
gateway 192.168.4.1

And then restart the network services by rebooting or running systemctl restart networking?

Question

If I make this change (I'll certainly be waiting for the communities feedback before proceeding) and it doesn't work and I lose access to Proxmox. What are my options?

Many thanks for taking the time to answer such a basic question. I rarely need to touch the inner workings of my setup so I'm rusty, and had limited knowledge to begin with! Let me know if I can provide any more information.

rason · Dec 11, 2022

Based on your information, it looks like you will need to update the network interface settings in the etc/network/interfaces file to reflect your new network setup. This will involve updating the address, netmask, and gateway values to match your new router's settings. You will also need to update the etc/hosts file to reflect the new IP address for your Proxmox server.
Here is an example of what your updated etc/network/interfaces file might look like:

Code:

auto lo
iface lo inet loopback
iface enp4s0 inet manual
auto vmbr0
iface vmbr0 inet static
address 192.168.4.115
netmask 255.255.252.0
gateway 192.168.4.1
bridge_ports enp4s0
bridge_stp off
bridge_fd 0
iface eno2 inet manual

And here is an example of what your updated etc/hosts file might look like:

Code:

127.0.0.1 localhost.localdomain localhost
192.168.4.115 mb1.local mb1
# The following lines are desirable for IPv6 capable hosts

::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

Once you have updated these files, you should be able to access your Proxmox server again through the Web UI or via SSH after restarting the network services. As always, it's a good idea to make a backup of your configuration files before making any changes, just in case something goes wrong.
Speaking of your options in case you lose access to Proxmox: physical access (display + keyboard) to the server is desired in case you are not able to connect to your machine.

Hope this helps!

Dunuin · Dec 11, 2022

mikeebee said:
Next steps
Assuming I don't need to change the IP address I currently use to access Proxmox (192.168.1.115) do I just need to change the netmask and gateway in etc/network/interfaces to this?

Code:

netmask 255.255.252.0 gateway 192.168.4.1

And then restart the network services by rebooting or running systemctl restart networking?

Another option would be to log in into your routers webUI and search for an option to change the routers IP, so it is working with a 192.168.1.0/24 subnet like your old router. Saves a lot of troubles, as you don't need to change the IPs of all your LANs hosts and guests.

And if you decide to to change the IP of PVE, keep in mind that you might also need to change the IPs of all VMs/LXCs in case they are not using DHCP. You also need to change the PVE IP, gateway and dns server in "/etc/network/interfaces", "/etc/hosts" as well as "/etc/resolv.conf".

mikeebee said:
Question
If I make this change (I'll certainly be waiting for the communities feedback before proceeding) and it doesn't work and I lose access to Proxmox. What are my options?

You connect a display and keyboard to your server, and change those 3 config file from the local console.

mikeebee · Dec 13, 2022

Thanks so much for the 2 solutions. This is just what I was looking for.

I am going to go with updating the Proxmox internals as opposed to the router, I have very few VM's so I don't mind making a couple of needed changes.

One thing I'm still not clear on is how to access the local console. I have a keyboard and display plugged into the server. On startup, I see the bios startup screen, then a Proxmox startup screen. At this point, I can press the "e" key to stop the boot sequence to edit the server/boot config but I have no idea how to access the command prompt. Once I proceed and start Proxmox the screen is blank.

I assume this is because I have GPU passthrough enabled? What can I do?

I wanted to post the contents of the server/boot config but I can't find the command needed in the terminal, could you tell me how to do this also, please?

Once I'm comfortable that I can access the local console I will proceed with the network changes.

Thanks again

Dunuin · Dec 13, 2022

mikeebee said:
One thing I'm still not clear on is how to access the local console. I have a keyboard and display plugged into the server. On startup, I see the bios startup screen, then a Proxmox startup screen. At this point, I can press the "e" key to stop the boot sequence to edit the server/boot config but I have no idea how to access the command prompt. Once I proceed and start Proxmox the screen is blank.

I assume this is because I have GPU passthrough enabled? What can I do?

Jup. You shouldn't passthrough your only GPU or at least not set the VM to autostart. Now the PVE host got no GPU to show you the console.
One option would be to go into the BIOS and disable IOMMU. Without that the passthrough won't work and starting the VM will fail, so the PVE host keeps that GPU, so you can access the console. But that of cause will only work in case you didn`t backlisted the GPU drivers.

In case you blacklisted the drivers, you could boot a Live Linux, mount the filesystems and try to comment out those blacklistings.

mikeebee · Dec 18, 2022

Ok all sorted! I removed the GPU blacklist before I made any changes just to make sure I could still access the console.

I updated the network settings as suggested and I'm back up and running.

Many thanks!

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[SOLVED] Changing routers, what network interface changes are needed?

mikeebee

Member

Here is my original network setup

Here is my new network setup

This is the output of nano etc/network/interfaces

This is the output of nano etc/hosts

Setup info

Next steps

Question

rason

Member

Dunuin

Distinguished Member

Next steps

Question

mikeebee

Member

Dunuin

Distinguished Member

mikeebee

Member

[SOLVED] Changing routers, what network interface changes are needed?

mikeebee

Member

Here is my original network setup​

Here is my new network setup​

This is the output of nano etc/network/interfaces​

This is the output of nano etc/hosts​

Setup info​

Next steps​

Question​

rason

Member

Dunuin

Distinguished Member

Next steps​

Question​

mikeebee

Member

Dunuin

Distinguished Member

mikeebee

Member

Here is my original network setup

Here is my new network setup

This is the output of nano etc/network/interfaces

This is the output of nano etc/hosts

Setup info

Next steps

Question

Next steps

Question