mira, yo uso freenet6, para debien tenes un paquete que es el tspc o freenet6 (no hay como el apt!)
la eth0 la tengo por dhcp a fiber y la eth1 la uso para darle conexion a las otras maquinolas.
Ahora meti un dhcp para compartir la red, porque hasta ahora lo mando a mano, asi me asigna bien un ipv6 a la eth1, pero tengo que configurar los clientes, jeje, un quilombo como veras.
sobre todo para meter ipv6 en un guin (no tengo la mas puta idea de como hacerlo) jeje

eth0      Link encap:Ethernet  HWaddr 00:48:54:1F:BC:53
          inet addr:MailScanner warning: numerical links are often malicious: 24.232.233.112  Bcast:MailScanner warning: numerical links are often malicious: 255.255.255.255  Mask:MailScanner warning: numerical links are often malicious: 255.255.255.0
          inet6 addr: fe80::248:54ff:fe1f:bc53/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:24486824 errors:0 dropped:0 overruns:0 frame:0
          TX packets:407442 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1960748975 (1.8 GiB)  TX bytes:60798288 (57.9 MiB)
          Interrupt:17 Base address:0xec00

eth1      Link encap:Ethernet  HWaddr 00:48:54:1F:E0:83
          inet addr:MailScanner warning: numerical links are often malicious: 10.0.0.55  Bcast:MailScanner warning: numerical links are often malicious: 10.255.255.255  Mask:MailScanner warning: numerical links are often malicious: 255.0.0.0
          inet6 addr: fe80::248:54ff:fe1f:e083/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:336789 errors:0 dropped:0 overruns:0 frame:0
          TX packets:461067 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:44199274 (42.1 MiB)  TX bytes:488098113 (465.4 MiB)
          Interrupt:18 Base address:0xe800

lo        Link encap:Local Loopback
          inet addr:MailScanner warning: numerical links are often malicious: 127.0.0.1  Mask:MailScanner warning: numerical links are often malicious: 255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:37056 errors:0 dropped:0 overruns:0 frame:0
          TX packets:37056 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2793691 (2.6 MiB)  TX bytes:2793691 (2.6 MiB)