Lost networking in all my KVM hosts

M

mxairman

Guest
Hello.

I'm running Proxmox on a dedicated server, and I'm running 5 virtual machines using KVM. Everything was working perfectly, but today, I wasn't able to access the VM's. Initially I could ping on their IPs (with no internet access though), but, after I rebooted the Proxmox server, I've only been able to access the Proxmox host and the VMs are unreachable (they are, only via VNC). This came with no configuration changes on Proxmox or on the VMs (actually I wasn't even home). I tried to update Proxmox and the problem still remains.

Here's my /etc/network/interfaces (which ran well before and hasn't been modified):
Code:
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
        address  xx.31.74.168
        netmask  255.255.255.0
        gateway  xx.31.74.1
        post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp


auto vmbr0
iface vmbr0 inet static
        address  10.10.10.1
        netmask  255.255.255.0
        bridge_ports none
        bridge_stp off
        bridge_fd 0
Here's the input of ifconfig (with 2 VMs on)
Code:
eth0      Link encap:Ethernet  HWaddr 00:26:b9:8f:5a:59  
          inet addr:xx.31.74.168  Bcast:xx.31.74.255  Mask:255.255.255.0
          inet6 addr: fe80::226:b9ff:fe8f:5a59/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12424 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3903 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1070817 (1.0 MiB)  TX bytes:1844640 (1.7 MiB)
          Interrupt:16 Memory:da000000-da012800 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8919 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8919 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2773279 (2.6 MiB)  TX bytes:2773279 (2.6 MiB)

vmbr0     Link encap:Ethernet  HWaddr 6a:ec:f9:43:b3:06  
          inet addr:10.10.10.1  Bcast:10.10.10.255  Mask:255.255.255.0
          inet6 addr: fe80::f828:cbff:fe8d:800e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:252 (252.0 B)  TX bytes:468 (468.0 B)

vmtab101i0 Link encap:Ethernet  HWaddr 6a:ec:f9:43:b3:06  
          inet6 addr: fe80::68ec:f9ff:fe43:b306/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:378 (378.0 B)  TX bytes:468 (468.0 B)

vmtab102i0 Link encap:Ethernet  HWaddr c6:66:53:59:f8:12  
          inet6 addr: fe80::c466:53ff:fe59:f812/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:0 (0.0 B)  TX bytes:468 (468.0 B)
Thank you in advance, and Regards.

mxairman
 
...
Here's my /etc/network/interfaces (which ran well before and hasn't been modified):
Code:
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
        address  xx.31.74.168
        netmask  255.255.255.0
        gateway  xx.31.74.1
        post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp


auto vmbr0
iface vmbr0 inet static
        address  10.10.10.1
        netmask  255.255.255.0
        bridge_ports none
        bridge_stp off
        bridge_fd 0
...

mxairman
Hi,
are you sure, that this config work before?
The traffic go through vmbr0, which is impossible without bridged interface...

Udo
 
Hello. Thanks for the replies.

This config was working for 2 months with no problem. Every VM has a dedicated ip (provided by the hosting company), and in every guest I set eth0 with static ip address (eg. xx.31.74.169, netmask 255.255.255.0 gateway xx.31.74.1 for VM101).

If this is not the correct way, can you point me to the right direction on how to set up the networking assigning those dedicated IPs to the guests?

I havent played around with the firewall, so it is mainly a default proxmox install.

If it helps, the hosting company did router changes few days ago. Then yesterday I could ping on all the addresses (the host + 5 gusts) but no ssh into them. Then the hosting company did a manual reset on the server, and then I could only ping and ssh into the proxmox host (also web interface working normally) but now I can't even ping into the hosts... only VNC access. I'm really desperate cause my customers have been more than 24 hours without access to their VPSs.

Thank you very much in advance,

mxairman
 
If this is not the correct way, can you point me to the right direction on how to set up the networking assigning those dedicated IPs to the guests?

You already said that it worked before, and you did not change anything.

If it helps, the hosting company did router changes few days ago.

try to use 'tcpdump' to see where packets gets lost.
 
Hello.

I notice the mac address changed. On vmtab101i0 it is now: HWaddr a2:ed:d5:e7:12:49, and on the virtual machine its 42:7E:EE:64:81:47. Before they used to be the same. Do you think that change is causing the problem, and if it is, how can i match both addresses again?

Thank you
 
So what would be a network setup if i want to run the Proxmox host with public ip xx.xx.xx.168 (which it already does), and the KVM guests on xx.xx.xx169, xx.xx.xx.170, etc, respectively? Any help will be really really appreciated.

mxairman
 
Hello. I finally sorted it out.
My pool of public IPs was from xx.31.74.168 to xx.31.78.173.
netmask 255.255.255.0
gateway: xx.31.74.1

Now /etc/network/interfaces looks like this:
Code:
auto lo
iface lo inet loopback

iface eth0 inet manual

iface eth1 inet manual

auto vmbr0
iface vmbr0 inet static
        address  xx.31.74.168
        netmask  255.255.255.0
        gateway  xx.31.74.1
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0

Then i configured the virtual machines with xx.31.74.169 (and so on), netmask 255.255.255.0, gateway xx.31.74.1

And everything is back to normal. I never rebooted with the previous configuration, so I guess thats why it got wrong when it was rebooted.

Hope this is useful for someone else, and thanks for the great work at Proxmox


mxairman
 

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