[SOLVED] no network after power fail

[Alexander Heidenreich]

Dear people,

we have a Proxmox VM server here and after the UPS got out yesterday, it crashed hard. Since then the network no longer works. Quick to setup, this is a relatively small server, which is why it only has a NIC, it is connected to a managed switch and a hybrid port. The management VLAN falls out of the port natively and untagged, all other VLANs are tagged. The switch was not affected by the power outage and I have already tested it with a different system and the same cable that connects the VM server and the port behaves as it should. It is also noticeable that the port has a link to the port during the post phase of the mainboard, PXE boot is possible. I therefore think a hardware defect is unlikely.
The VM server had been running unchanged for months and had an uptime of several weeks before the hard shutdown. Attached is a screenshot of the network on Linux, which looks ok to me at first, but no pings come through. The system is also not reachable by web frontend or SSH.10.110.9.21 is the management IP, the .1 is the defgw.

Small addition, when I run dhclient enp7s0, the port goes up.

How can I debug this further?

 

[Alexander Heidenreich]

ifreload -a doesn't help.

nothing meaningfull in the logs anywhere

 

[cheiss]

Hi,

what's the output of cat /etc/network/interfaces (the actual network configuration) and ip r (routing table)?
Possibly the gateway/routes are not set up correctly, on a hunch.

 

[Alexander Heidenreich]

Everything was correct in this, but...

Your question/tip brought me on the right way. I checked /etc/network/interfaces first when this problem occured and didn't find anything unusual. I can't recall if I used nano or vi, but when I checked with cat I've noticed something I didn't before. Behind the line declaring the bridge-interface was a strange character, never seen before. I presume the file was corrupted (shouldn't happen because the file was not opened for months) during the crash or maybe when the file system was checked and "corrected" after the first restart. This shouldn't happen, but sometimes mystherious things are happening...

I rewrote /etc/network/interfaces from scratch and it works like before. I really wonder why nothing meaningful was in a logfile or journal.

Guys, take care of your UPS or you will be punished later!

 

[cheiss]

Great you could solve it yourself in the end!

Please just mark the thread as SOLVED by editing the first post, there should be a dropdown near the title field - this helps others find it more easily in the future