Here's an example log (obtained while running dibbler with the '-f -d' options, and redirecting output to a file with tee). If I trace the traffic using tcpdump I see three DHCPv6 solicit messages being sent and no reply.
| Dibbler - a portable DHCPv6, version 0.4.2 (SERVER, Linux port) | Authors : Tomasz Mrugalski<thomson(at)klub.com.pl>,Marek Senderski<msend(at)o2.pl> | Licence : GNU GPL v2 or later. Developed at Gdansk University of Technology. | Homepage: http://klub.com.pl/dhcpv6/ 06:53:57 Notice My pid (1040) is stored in /var/lib/dibbler/server.pid 06:53:57 Notice Detected iface sit0/4, MAC=00:00:00:00. 06:53:57 Notice Detected iface eth1/3, MAC=00:0c:29:7c:66:e8. 06:53:57 Notice Detected iface eth0/2, MAC=00:0c:29:7c:66:de. 06:53:57 Notice Detected iface lo/1, MAC=00:00:00:00:00:00. 06:53:57 Notice Parsing /etc/dibbler/server.conf config file... 06:53:57 Info Interface eth1/3 configuration has been loaded. 06:53:57 Notice Running in stateful mode. 06:53:57 Info My duid is 00:01:00:00:45:04:63:97:00:0c:29:ba:68:67. 06:53:57 Notice Creating multicast (ff02::1:2) socket on eth1/3 (eth1/3) interface. 06:53:57 Notice Accepting connections. Next event in 4294967295 second(s). 06:58:36 Warning Option type 8 invalid. Option ignored. 06:58:36 Notice Received SOLICIT on eth1/3,TransID=0x3c9869, 3 opts: 2 3 6, 0 relay(s). 06:58:36 Warning Invalid message received. 06:58:36 Notice Accepting connections. Next event in 4294967295 second(s). 06:58:37 Warning Option type 8 invalid. Option ignored. 06:58:37 Notice Received SOLICIT on eth1/3,TransID=0x3c9869, 3 opts: 2 3 6, 0 relay(s). 06:58:37 Warning Invalid message received. 06:58:37 Notice Accepting connections. Next event in 4294967295 second(s). 06:58:39 Warning Option type 8 invalid. Option ignored. 06:58:39 Notice Received SOLICIT on eth1/3,TransID=0x3c9869, 3 opts: 2 3 6, 0 relay(s). 06:58:39 Warning Invalid message received. 06:58:39 Notice Accepting connections. Next event in 4294967295 second(s).