[Kea-users] DHCP6 subnet select fails. Basic config

[Francis Dupont]

Tim Howe writes:
> 	I somehow managed to not make it part of my paste in my
> previous email, but I am attempting to select the subnet based on the
> interface-id (option-18).

=> so you have a relay.

>  "subnet6": [
>         {
>             "interface-id": "3/2/1/1",
>             "subnet": "2607:fda0:101:1601::/64",
>             "pools": [ { "pool": "2607:fda0:101:1601:4::/80" } ]
> 
> I see it in the debug log data:
> link-address=::, peer-address=fe80::1e74:dff:fe4b:cd76, 1 option(s)
> type=00018, len=00007: 33:2f:32:2f:31:2f:31

=> the link-address must not be :: cf RFC 3315 20.1.1 page 59.
This is critical because it is the way Kea subnet selection recognizes
direct vs relayed incoming packets (*).

> 	However, Kea appears to be ignoring it or is failing to match
> it against the string as I have written it.
> 
> 	I also tried specifying the interface-id in a few different
> ways such as "'3/2/1/1'", "33:2f:32:2f:31:2f:31", and "332f322f312f31",
> but it fails to match on all of them.  Is there some other trick to
> getting that to match?

=> interface-id is used as an option with the content set from the
string in the config so it is "3/2/1/1". If you have strange bytes in
it you have to use unicode escape. Note as far as I know nobody uses
something else than ASCII even it is just an opaque vector of bytes...

> 	I am running Kea 1.2.0 still, is this by any chance a known bug
> I can fix by upgrading? (been waiting for FreeBSD port to get
> refreshed).

=> I am afraid that upgrading Kea won't help.

Regards

Francis Dupont <fdupont at isc.org>

PS: the algorithm for Kea subnet6 selection is:

if first_relay_linkaddr is ::
 // directly connected client
 if interface name is not ""
   try subnet6 with this interface name
 if remote address is not ::
   try subnet6 with this remote address
else
 // relayed message
 try interface id
 try link address