Documentation for virConnectOpenAuth is a bit light at the moment. I found: http://libvirt.org/html/libvirt-libvirt.html#virConnectOpenAuth http://libvirt.org/auth.html This is the most serious omission from the documentation: http://libvirt.org/html/libvirt-libvirt.html#virConnectAuthCallbackPtr virConnectAuthPtrDefault is a default implementation of the callback that you should use for command-line tools. It's used in virsh.c. It's not documented at all, but the source for it (in libvirt.c) does give a little bit of guidance. Anyway, as long as there isn't some font of documentation for this call which I've missed, I'll have a go at writing some while I write the OCaml binding. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into Xen guests. http://et.redhat.com/~rjones/virt-p2v