dhcpcd - making it Work By Default

[Roy Marples <roy%marples.name@localhost>]

Hi List

So there's been some debate about dhcpcd vs dhclient. I am trying to 
remain neutral in these discussions as I have a very obvious bias but 
what I did pick up on was a few people saying that dhcpcd doesn't Work 
By Default. This post will address this.

There are only two reasons why dhcpcd *may* not work by default when it 
expected to do so:
1) Interface resets when changing MTU
2) a client ID is not sent

Now, when I first introduced dhcpcd into NetBSD 1) was a known issue 
with specific drivers and various people said that would fix or work 
around this in the respective drivers. This has not happened, so in 
dhcpcd-6 MTU request will be disabled by default.

Some DHCP servers (notably the Fritz! routers) actively require a 
clientid to be sent. The only DHCPv4 client which does not send a client 
id by default is ..... dhclient! Note that Windows, OSX, etc do sent a 
client id. So in dhcpcd-6, a default clientid will be sent.

With this in mind, we can send a variety of default clientid's
a) HWADDR based (like Windows, OSX)
b) DUID-LL(T) based as mandated by DHCPv6

So that the Works By Default crowd is satisfied I'll probably go with 
a), but am open to arguments to go with b).

Now, if you've read this and maybe even modified dhcpcd.conf(5) to 
reflect the above and dhcpcd fails to work by default then please tell 
me either by email, a ticket at the dhcpcd project page or a NetBSD PR 
instead of just saying "it doesn't work and requires too much reading". 
I can't improve it if I don't know about your problems!

Thanks

Roy