Networking problem that I can't get to the bottom of

[SteveT1970]

I have been having a problem with my Proxmox server's networking so I gave up and wiped it and reinstalled Proxmox from scratch. I still have the problem and it seems to be something about Proxmox.

I know this is going to be something simple and I just need to tweak something somewhere. The network here is my home network. I don't use VLANs, just 192.168.0.0/21 which is split in "theoretical" ranges only. 192.168.1.x is the infrastructure - switches, etc. 192.168.6.x is the "home" network - if you get an address by DHCP it's in the range 192.168.6.50 - 250, Raspberry Pis are put on 192.168.7.x and so on.

But to be clear, my network is completely flat.

My DNS server has the address 192.168.6.1, subnet mask 255.255.248.0 and gateway 192.168.1.1

My Proxmox server usually (pve) has the address 192.168.1.10, subnet mask 255.255.248.0 and gateway 192.168.1.1 It cannot see the DNS server (zentyal)

administrator@zentyal:~$ ping 192.168.1.10 -c 4
PING 192.168.1.10 (192.168.1.10) 56(84) bytes of data.
64 bytes from 192.168.1.10: icmp_seq=1 ttl=64 time=0.316 ms
64 bytes from 192.168.1.10: icmp_seq=2 ttl=64 time=0.364 ms
64 bytes from 192.168.1.10: icmp_seq=3 ttl=64 time=0.344 ms
64 bytes from 192.168.1.10: icmp_seq=4 ttl=64 time=0.267 ms

--- 192.168.1.10 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3053ms
rtt min/avg/max/mdev = 0.267/0.322/0.364/0.042 ms


root@pve:~# ping 192.168.6.1 -c 4
PING 192.168.6.1 (192.168.6.1) 56(84) bytes of data.

--- 192.168.6.1 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 79ms

And...

root@pve:~# dig +short www.google.com @192.168.6.1
;; connection timed out; no servers could be reached

But if I change its address to something on 192.168.6.x

root@pve:~# cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

auto vmbr0
iface vmbr0 inet static
    address 192.168.6.2
    netmask 255.255.248.0
    gateway 192.168.1.1
    bridge_ports eno1
    bridge_stp off
    bridge_fd 0

It starts working. It's as though the Proxmox server can only see addresses in the 255.255.255.0 subnet even though it's set to 255.255.248.0. This is "confirmed" by setting the address to 192.168.2.2 - it stops working again. But it can see 192.168.1.1

Can anyone see what I'm missing? Obviously putting it on 192.168.6.2 "fixes" it but I'd like to understand what's "broken".

Thanks,

Steve

 

[Stoiko Ivanov]

The config should work from a quick glance.

please check the output of:
* `ip addr show`
* `ip route show`
* `ip link show`

To see what's actually configured

I hope this helps!