Do you install OMV on Debian with a GUI? Problems with DNS / Network disconnecting? Use NetworkManager? Read this.

ellnic · 5. Januar 2018

A friend of mine took my advice and started to use OMV recently. Like me, he wanted to have a full DE to work with. The easiest way to do this (for me at least, and thus he took the same path) is to install Debian 8 (Jessie), then add OMV 3 repos and install. I think this method is quite popular and it's certainly my go to method of install.

He was having some weird occasional net disconnection issues that we couldn't quite figure out. If you left the box alone to do it's thing (Plex and Samba) it would run for weeks for the most part. But as soon as you tried to VNC or TeamViewer into it, it would disconnect and throw a fit. We initially thought it was just TeamViewer disconnecting, then someone suggested it could be an Avahi issue, but it wasn't.

The problems experienced were:

1. Random network disconnects - no ping from router
2. Network disconnects triggered by TeamViewer or VNC connection/disconnection (this is what highlighted the problem)
3. Other net disconnection issues, but oddly, no issues with normal resolving when the net was up and running ie. browsing the net or fetching updates

The problems seemed to be more of a network failing issue rather than that of a DNS issue, so it threw us off for a bit. However, it turns out this is a Debian installation Network/NetworkManager bug that causes DNS to be incorrectly configured. I've not come across it before because I don't use NetworkManager, but NetworkManager is installed by default in Debian 8 when installing a GUI. If you opt to keep NetworkManager and use it, you should check this.

If you just use the OMV 3 installation image, you will not have this problem, as NetworkManager is not installed.

Indeed, NetworkManager is NOT required and if you're connecting via ethernet (which you should be in 99% of cases) it's better to use /etc/network/interfaces which can be managed via OMV.

However, installing Debain 8 with a DE and thus NetworkManager by default triggers this bug. It is the result of the switch from dnsmasq to resolvconf and for some reason, Network Manager is still being configured to use dnsmasq. NetworkManager should also ignore anything specified in /etc/network/interfaces so if using OMV to configure or manually configuring yourself, you probably haven't come across this. If using dnsmasq, you also probably have no need for this info.

However, if you install Debian Jessie, connect to the net using NetworkManager, then add OMV repos and install (as was the case here), you might need to check your conf file.

You have 2 options at this point:

1. Correct the erroneous conf file and keep using NetworkManager

2. Remove NetworkManager - network manager is not needed if you are only using Ethernet. It doesn't have a squeaky clean history of solid network connections, and is best avoided in a server environment. If you're only using Ethernet, consider ditching it

So:

1. Correct the erroneous conf file:

Open a terminal and get root privs:

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sudo -s

Then open the NetworkManager configuration file for editing:

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nano /etc/NetworkManager/NetworkManager.conf

You are looking for an entry here that might be obvious now - it's dns=dnsmasq. Yup, NetworkManager is trying to use dnsmasq, but it's not installed.

Change it to dns=default

You should also change managed to true, as shown to give NetworkManager full control over interfaces.

Now press Control-X then 'Y' then [Enter] to save.

Now you can either:

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reboot now

Or if you don't want / can't do this, restart NetworkManager and Networking:

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systemctl restart NetworkManager.service && systemctl restart networking.service

2. Remove NetworkManager and use OMV to configure network interfaces (preferred)

In a terminal:

Get root privs:

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sudo -s

Remove NetworkManager:

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apt-get remove --purge network-manager

Now run OMV first aid to get you on the net:

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omv-firstaid

Run through the steps in option 1 to get you up and running on the net.

Now use the OMV interface to change any required settings.

Done Hope this was helpful and avoids any premature bald patches. As a side note, anyone who also runs Ubuntu 16.04 or any of its flavours that come with a full DE, you also need to check this. The bug was taken from Jessie and NOT fixed by the Ubuntu team either. Confirmed this in a VM. Apparently this has been fixed in Stretch so fresh installs of OMV 4 on Debian 9 should not have this issue. Same applies to the newer Ubuntu's based on Stretch.

I hope this is helpful.

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