DHCP v6 static mappings for multiple interfaces on a host (DUID+IAID)

[Mks]

Hi,

I'm testing IPv6 in my local network and want to assign static IPs to machines (mainly Windows) with multiple interfaces:

As far as I know the DUID identifies the HOST, the IAID identifies the interface
Unfortunatly there is no option for IAID in opnsense "DHCPv6 Static Mappings", so if I have multiple interfaces on a host I cannot assign static IPs for each of them.

How can this be solved?

OPNsense 18.7.9-amd64
FreeBSD 11.1-RELEASE-p17
OpenSSL 1.0.2q 20 Nov 2018

Thanks

[9axqe]

I just noticed the same issue today (Home Assistant with LAN and WLAN both connected during a network modification). This is quite problematic, because opnsense will happily assign the same IPv6 to different interfaces, causing all sorts of fun effects, both on the device in question and in the network...

Not sure if it's an ISC limitation or rather an opnsense limitation.

[bartjsmit]

Just add them on the (Windows) host. IPv6 can have a whole bunch of unicast/multicast/local/routable/static/dhcp/slaac addresses on the same host and there are always plenty to choose from.

E.g. I am moving a headless host between IPv4 subnets, so I added a static fdab:feed:face::1 to my laptop WiFi interface and fdab:feed:face::2 to the host and confirmed I can get to the host web interface on https://[fdab.feed.face::2] quite easily. I didn't do anything to the rest of the network at all.

One of the biggest hurdles in IPv6 seems to be 'IPv4 thinking' - like why people use DHCPv6 on a home network ;-)

Bart...

[dseven]

According to https://kb.isc.org/docs/isc-dhcp-44-manual-pages-dhcpdconf :

"When dhcpd tries to find a host declaration for a client, it first looks for a host declaration which has a fixed-address declaration that lists an IP address that is valid for the subnet or shared network on which the client is booting. If it doesn't find any such entry, it tries to find an entry which has no fixed-address declaration."

So you should be able to add static mappings with the same DUID on multiple different interfaces (with fixed addresses from the respective subnets), and the DHCP server should do the right thing.

@Mks have you actually tried to do this, and found it to not work? BTW, OPNsense 18.7 is very old at this point!