dhcpd still doesn't work on tunnel interfaces?

[Phil Mayers]

All,

I would like to respond to DHCPv6 requests received via a GRE tunnel 
interface on Linux. There are mentions in the archives in 2006/2007 
about dhcpd having "hard-coded" assumptions of ethernet-like interfaces, 
and therefore not being able to work in this manner, even for receiving 
unicast, relayed packets.

This seems to still be the case under 4.1 - is there any chance it will 
ever be fixed?

I am specifically trying to work around a bug in Cisco IOS, where the 
DHCPv6 relay function does not work if the next-hop is an MPLS-labelled 
path. You can work around this by building a GRE tunnel from the 
router(s) to the DHCP server(s) - if ISC dhcpd would respond that is, 
which it won't :o(

I am aware "fixing IOS" is the right approach, but Cisco aren't 
interested. They deny that it's even a bug, claiming that it's "not 
supposed to work in that config", and no amount of pushing has succeeded 
in changing that PoV.