DUID-LL generation

[robert.haugen@gmail.com]

Hello.

According to my knowledge, the DUID-LL value is generated on the basis of the MAC address. Today, when I clicked "Insert a new LL DUID", a new "DHCP Unique Identifier" is generated. The MAC address is not changed. Should´t this value be the same every time?

[marjohn56]

In Theory. Quite often what happens is that the ISP will supply their client a router and lock their system to the MAC address based DUID of that supplied router, when the client uses their own they have to clone the DUID of the supplied router to their own. What can also happen is that when that is not the case, i.e. it's not locked to a specific DUID the client can use a random DUID and that usually forces the ISP BNG to allocate a different address/range. You'll fine DUID-LLT is more common where a timestamp is added to the DUID-LL, this means that it may change when you reset the router anyway so it's not a fixed 'has to comply' rule. With all that you have to be careful as some ISPs will only accept a DUID-LL length DUID or only a DUID-LLT... all gets a bit hairy as I found out years ago with Sky U.K.

[Maurice]

The "new LL / LLT DUID" feature uses the MAC address of the device which you use to access the Web UI, not a MAC address of the OPNsense machine itself.

Cheers
Maurice

[marjohn56]

Thanks Maurice, hadn't noticed that. Cannot say I am keen on that idea, random would be my preferred choice. Not that I am that bothered, I always clone the DUID anyway.

[robert.haugen@gmail.com]

Thanks Maurice :-)