I've installed Xen and libvirt on a CentOS 6.6 machine. All the tools (virt-manager, virsh etc) work perfectly as root (directly or via sudo) but I cannot allow another user to connect (failed to connect/DBus error).

**My Configuration**

I followed the procedure for allowing user access by creating a group and allowing this through polkit so I've:

 groupadd virtadmin
 usermod -a -G virtadmin davec

I also added myself to the KVM group (a suggestion found somewhere). The group is created and I'm in it as id outputs:

 uid=500(davec) gid=500(davec) groups=500(davec),36(kvm),501(virtadmin)

To allow this in polkit I added the file /etc/polkit-1/localauthority/50-local.d/50-libvert-remote-access.pkla content:

 Remote libvirt SSH access]
 Identity:unix-group:virtadmin
 Action:org.libvirt.unix.manage
 ResultAny=yes
 ResultInactive=yes
 ResultActive=yes

After this didn't work some googling told me that newer polkit versions (yum tells me I have 0.96) use a rules-based approach so I've also created a folder /etc/polkit-1/rules.d and added the file 80-libvirt-manage.rules containing:

 polkit.addRule(function(action, subject) {
 if (action.id == "org.libvirt.unix.manage" && 
 subject.local && 
 subject.active && 
 subject.isInGroup("virtadmin")) {
 return polkit.Result.YES;
 }
 });

Now it may be that there is some problem with these but I can't find a log or any way it seems to test/verify/watch them.

So, according to the docs I've found, with that setup user davec should be able to access libvirt and run virsh or virt-manager.

**The Error**

 [davec@polar rules.d]$ virsh -c xen:///
 error: failed to connect to the hypervisor
 error: internal error: DBus support not compiled into this binary

This is exactly the same error virt-manager gives when I try and connect.

Most of the online info about the DBus error refers to a problem with the hypervisor running/anyone connecting however root connects perfectly.

 [davec@polar rules.d]$ sudo virsh -c xen:///
 Welcome to virsh, the virtualization interactive terminal.

Exactly the same applies for SSH connections (which isn't surprising as SSH just tunnels I believe when you use a xen+ssh URI), root works non-root but group added user doesn't.

No doubt it's something simple and I'm being an idiot but... after a few days of Google not being my friend; any help truly appreciated.

**The Answer**

See below for c4f4t0r's correct (and accepted) answer which wins the bounty but just for info of anyone reading this it turns out to be **nothing to do with polkit** which doesn't appear to be configured/compiled/working with my libvirtd.

Was an in-built permissions (socket permissions) issue.