I am relatively new to Linux and Vagrant. I updated my VM guest system (VirtualBox 5.0.18 + Vagrant 1.8.1 on a Windows Host) from Xubuntu 15.10 to Xubuntu 16.04 a while ago. At that point or shortly after I noticed some oddities, e.g. a misaligned mouse cursor (a few pixels off) and missing shared directories. My guess is that it's due to the following error reported during vagrant up:==> default: Clearing any previously set forwarded ports...==> default: Clearing any previously set network interfaces...==> default: Preparing network interfaces based on configuration...    default: Adapter 1: nat    default: Adapter 2: hostonly==> default: Forwarding ports...    default: 8080 (guest) => 8080 (host) (adapter 1)    default: 9000 (guest) => 9000 (host) (adapter 1)    default: 22 (guest) => 2222 (host) (adapter 1)==> default: Running 'pre-boot' VM customizations...==> default: Booting VM...==> default: Waiting for machine to boot. This may take a few minutes...    default: SSH address: 127.0.0.1:2222    default: SSH username: vagrant    default: SSH auth method: private key==> default: Machine booted and ready!GuestAdditions 5.0.18 running --- OK.==> default: Checking for guest additions in VM...==> default: Configuring and enabling network interfaces...The following SSH command responded with a non-zero exit status.Vagrant assumes that this means the command failed!/sbin/ifup eth1Stdout from the command:Failed to bring up eth1.Stderr from the command:mesg: ttyname failed: Inappropriate ioctl for devicerun-parts: /etc/network/if-up.d/ubuntu-fan exited with return code 1I looked for the error in combination with Vagrant and VirtualBox online, but the cases I found seemed all a bit different to mine. People write about /etc/udev/rules.d/70-persistent-net.rules - but it does not seem to exist on my machine, neither does /etc/sysconfig.Trying to run /sbin/ifup eth1 for some more information after logging in gives me this:vagrant@IDE-machine ~ $ sudo /sbin/ifup -v eth1Configuring interface eth1=eth1 (inet)/bin/run-parts --exit-on-error --verbose /etc/network/if-pre-up.drun-parts: executing /etc/network/if-pre-up.d/bridgerun-parts: executing /etc/network/if-pre-up.d/ethtoolrun-parts: executing /etc/network/if-pre-up.d/wireless-toolsrun-parts: executing /etc/network/if-pre-up.d/wpasupplicant/bin/ip addr add 192.168.56.21/255.255.255.0 broadcast 192.168.56.255     dev eth1 label eth1RTNETLINK answers: File existsFailed to bring up eth1.My Vagrant file looks like this:Vagrant.configure(2) do |config|  # a locally stored box  config.vm.box = IDE-machine  config.ssh.private_key_path = ssh/id_rsa  config.vm.network forwarded_port, guest: 8080, host: 8080  config.vm.network forwarded_port, guest: 9000, host: 9000  config.vm.network private_network, ip: 192.168.56.21  config.vm.provider virtualbox do |vb|      vb.gui = true      vb.memory = 12288      vb.cpus = 2      vb.name = my_IDE-machine      vb.customize [modifyvm, :id, --monitorcount, 1]      vb.customize [modifyvm, :id, --vram, 64]      vb.customize [storageattach, :id, --storagectl, SATA, --port, 1, --device, 0, --type, hdd, --medium, V:/BoxStorage/Projects.vdi]  end  config.vm.provision shell, inline: /vagrant/provision.shendGuest additions are installed, I use the vagrant-vbguest plugin which had set up the right guest addon version earlier.Does someone have an idea what could be the issue, or hints how I can dig further?Update:I was pointed to this: https://github.com/mitchellh/vagrant/issues/7155 (which does not apply completely to my case)Which led me to this: https://github.com/mitchellh/vagrant/issues/7155https://askubuntu.com/questions/689070/network-interface-name-changes-after-update-to-15-10-udev-changes/732638#732638I tried changing /etc/default/grub with GRUB_CMDLINE_LINUX=net.ifnames=0, then update-grub as root and reboot, to no avail.Some more poking around showed me this:vagrant@IDE-machine ~ $ cat /etc/network/interfaces# interfaces(5) file used by ifup(8) and ifdown(8)auto loiface lo inet loopback#VAGRANT-BEGIN# The contents below are automatically generated by Vagrant. Do not modify.auto eth1iface eth1 inet static      address 192.168.56.21      netmask 255.255.255.0#VAGRANT-ENDUpdate 2: As requested here is the output of dmesg and the contents of ubuntu-fan:vagrant@IDE-machine ~ $ dmesg | grep eth[    1.692133] e1000 0000:00:03.0 eth0: (PCI:33MHz:32-bit) 08:00:27:af:31:b4[    1.692144] e1000 0000:00:03.0 eth0: Intel(R) PRO/1000 Network Connection[    2.068113] e1000 0000:00:08.0 eth1: (PCI:33MHz:32-bit) 08:00:27:94:1e:dc[    2.068120] e1000 0000:00:08.0 eth1: Intel(R) PRO/1000 Network Connection[    5.732516] e1000: eth1 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX[    5.732980] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready[    5.733061] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready[    6.790923] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready[    6.793512] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready[    6.795646] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX[    6.796069] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes readyvagrant@IDE-machine ~ $ cat /etc/network/if-up.d/ubuntu-fan #!/bin/shset -ecase $IFACE inlo) exit 0 ;;fan-*)  exit 0 ;;esaccase $ADDRFAM ininet) ;;*) exit 0 ;;esac# NOTE: NetworkManager simply does not call out to the normal#       down hooks as it only checks _after_ the interface has#       been lost.  Roll with this.case $PHASE::$METHOD inpost-up::static|post-up::dhcp|post-up::NetworkManager)          ;;pre-down::static|pre-down::dhcp|post-down::NetworkManager)      ;;*) exit 0 ;;esaccase $MODE instart|stop) ;;*) exit 0 ;;esac/usr/sbin/fanctl net $MODE $IFACE
Vagrant fails to bring up eth1 on Xubuntu 16.04 guest
virtualbox;xubuntu;vagrant
Did you check your /etc/network/interfaces config files ? Maybe you have several gateways as pointed here .Anyway, tweaking that file a bit and playing with ifconfig can help you drag the problem out. Check the permissions also, I doubt it comes from there but still :/You can try to go back to a simpler configuration in /etc/network/interfaces if it's not already the case and go back bit by bit to the original configuration file. I would do that I think.EDIT:From your dmesg output it seems that links are ready so the network part should be ok.If you make dmesg | grep eth, is there any relevant information ?Also, can you cat /etc/network/if-up.d/ubuntu-fan ? It exited with exit code 1, could be interesting to check what's happening there.UPDATE:You dmesg output seems okay, the links eth0/1 are ready in the end so the network should be working.You should try to execute the ubuntu-fan script line by line and check for exit codes (echo $?, should be 0). I wonder if the problem doesn't come from the fanctl program at the end. It is normaly used to control fans on a machine, but here it's a VM so ... If it's coming from this line, you can try to look why it's failing, but I would remove the fanctl line, and then maybe the whole file in fact. I guess the other lines are here to handle events to trigger fanctl.I have checked my vagrant VMs (mostly ubuntu 14.04 though) and I don't see any fanctl anywhere ... I  not sure it makes sense to try to control fans inside a VM.