Virtual Machine Manager Network Bridge

Hi all

I am very new to the Linux world but I want to learn which is why I have built myself a PC purely for running VMs so I can learn and experiment with stuff. I am running Ubuntu server 16.04LTS as my host OS with QEMU/KVM Virtual Machine Manager.

My original problem was permissions with using a secondary internal HDD as a storage pool for the VHDs, I found a post on here that suggested using User Session in Virt Manager to get around this. I now have an issue with the NICs for my VMs.

Before I could select with NIC to use however now I only have two options, “Usermode networking” or “Specify shared device name” with then the option to input a “Bridge name”. I have gone to Edit > Connection Details > Network Interfaces to configure a bridge however I get the following when trying to select the NIC I wish to use:

Error creating interface: ‘Could not define interface: internal error: could not get interface XML description: unspecified error - aug_save failed on /etc/network/interfaces: mk_augtemp (Permission denied)’

Details:

Error creating interface: ‘Could not define interface: internal error: could not get interface XML description: unspecified error - aug_save failed on /etc/network/interfaces: mk_augtemp (Permission denied)’

Traceback (most recent call last):
File “/usr/share/virt-manager/virtManager/asyncjob.py”, line 90, in cb_wrapper
callback(asyncjob, *args, **kwargs)
File “/usr/share/virt-manager/virtManager/createinterface.py”, line 1141, in do_install
self.interface.install(meter, create=activate)
File “/usr/share/virt-manager/virtinst/interface.py”, line 257, in install
raise RuntimeError(_(“Could not define interface: %s”) % str(e))
RuntimeError: Could not define interface: internal error: could not get interface XML description: unspecified error - aug_save failed on /etc/network/interfaces: mk_augtemp (Permission denied)

So my question is, what is the best way to resolve this?