Кстати, если кому интересно: авторизация через kerberos тоже ни к чему путнему не привела, а гугл молчит:
d [14/Jan/2013:11:00:15 +0900] [Client 17] con->uri="/admin/conf", con->best=0xb91f52a8(/admin/conf)
d [14/Jan/2013:11:00:15 +0900] [Client 17] Authorization="Negotiate 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"
D [14/Jan/2013:11:00:15 +0900] [Client 17] Credentials not complete: The routine must be called again to complete its function, Unknown error
d [14/Jan/2013:11:00:15 +0900] cupsdIsAuthorized: con->uri="/admin/conf", con->best=0xb91f52a8(/admin/conf)
d [14/Jan/2013:11:00:15 +0900] cupsdIsAuthorized: level=CUPSD_AUTH_USER, type=Negotiate, satisfy=CUPSD_AUTH_SATISFY_ALL, num_names=2
d [14/Jan/2013:11:00:15 +0900] cupsdIsAuthorized: auth=CUPSD_AUTH_ALLOW...
D [14/Jan/2013:11:00:15 +0900] cupsdIsAuthorized: username=""
d [14/Jan/2013:11:00:15 +0900] [Client 17] cupsdSendError code=401, auth_type=0
D [14/Jan/2013:11:00:15 +0900] [Client 17] WWW-Authenticate: Negotiate
D [14/Jan/2013:11:00:15 +0900] [Client 17] Closing connection.
вот это особенно доставляет: Credentials not complete: The routine must be called again to complete its function, Unknown error