This solution applies to all Barracuda common products.
"Your machine does not have access rights to login as the specified user" error occurs when an administrative IP range has been specified in the appliances configuration under the Basic > Administration > Administrator IP/Range.
If the requesting IP address does not fall within the defined IP ranges in this setting it will be denied access to the administrative interface of the the appliance.
To correct this, connect to the Barracuda appliances' administrative interface from a computer with an IP address that falls within the defined range and modify the defined IP address range as necessary to allow access where applicable.
If the device is still inaccessible please contact Barracuda Technical Support.
Link to this page:http://www.barracudanetworks.com/kb?id=50160000000HmOe